[Zodb-checkins] CVS: StandaloneZODB/Doc/guide/zodb - .cvsignore:1.2 about.html:1.2 contents.html:1.2 images.tex:1.2 img1.gif:1.2 index.html:1.2 node10.html:1.2 node11.html:1.2 node12.html:1.2 node13.html:1.2 node14.html:1.2 node15.html:1.2 node16.html:1.2 node17.html:1.2 node18.html:1.2 node19.html:1.2 node2.html:1.2 node20.html:1.2 node21.html:1.2 node23.html:1.2 node24.html:1.2 node25.html:1.2 node26.html:1.2 node27.html:1.2 node28.html:1.2 node29.html:1.2 node3.html:1.2 node30.html:1.2 node31.html:1.2 node32.html:1.2 node33.html:1.2 node34.html:1.2 node35.html:1.2 node36.html:1.2 node37.html:1.2 node38.html:1.2 node39.html:1.2 node4.html:1.2 node40.html:1.2 node41.html:1.2 node42.html:1.2 node43.html:1.2 node44.html:1.2 node45.html:1.2 node46.html:1.2 node47.html:1.2 node48.html:1.2 node49.html:1.2 node5.html:1.2 node50.html:1.2 node51.html:1.2 node52.html:1.2 node53.html:1.2 node6.html:1.2 node7.html:1.2 node8.html:1.2 node9.html:1.2 zeo.html:1.2 zodb.css:1.2 zodb.html:1.2
Guido van Rossum
guido@python.org
Mon, 11 Feb 2002 18:33:42 -0500
Update of /cvs-repository/StandaloneZODB/Doc/guide/zodb
In directory cvs.zope.org:/tmp/cvs-serv18412/zodb
Added Files:
.cvsignore about.html contents.html images.tex img1.gif
index.html node10.html node11.html node12.html node13.html
node14.html node15.html node16.html node17.html node18.html
node19.html node2.html node20.html node21.html node23.html
node24.html node25.html node26.html node27.html node28.html
node29.html node3.html node30.html node31.html node32.html
node33.html node34.html node35.html node36.html node37.html
node38.html node39.html node4.html node40.html node41.html
node42.html node43.html node44.html node45.html node46.html
node47.html node48.html node49.html node5.html node50.html
node51.html node52.html node53.html node6.html node7.html
node8.html node9.html zeo.html zodb.css zodb.html
Log Message:
Adding AMK's guide (merge)
=== StandaloneZODB/Doc/guide/zodb/.cvsignore 1.1 => 1.2 ===
+*.log
=== StandaloneZODB/Doc/guide/zodb/about.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>About this document ...</title>
+<META NAME="description" CONTENT="About this document ...">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="previous" HREF="node41.html">
+<LINK REL="up" HREF="zodb.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node53.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node53.html">ADDENDUM: How to use</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H1><A NAME="SECTION000900000000000000000">
+About this document ...</A>
+</H1>
+ <strong>ZODB/ZEO Programming Guide</strong>,
+February 8, 2002, Release 0.03
+<p> This document was generated using the <a
+ href="http://saftsack.fs.uni-bayreuth.de/~latex2ht/">
+ <strong>LaTeX</strong>2<tt>HTML</tt></a> translator.
+</p>
+
+<p> <a
+ href="http://saftsack.fs.uni-bayreuth.de/~latex2ht/">
+ <strong>LaTeX</strong>2<tt>HTML</tt></a> is Copyright ©
+ 1993, 1994, 1995, 1996, 1997, <a
+ href="http://cbl.leeds.ac.uk/nikos/personal.html">Nikos
+ Drakos</a>, Computer Based Learning Unit, University of
+ Leeds, and Copyright © 1997, 1998, <a
+ href="http://www.maths.mq.edu.au/~ross/">Ross
+ Moore</a>, Mathematics Department, Macquarie University,
+ Sydney.
+</p>
+
+<p> The application of <a
+ href="http://saftsack.fs.uni-bayreuth.de/~latex2ht/">
+ <strong>LaTeX</strong>2<tt>HTML</tt></a> to the Python
+ documentation has been heavily tailored by Fred L. Drake,
+ Jr. Original navigation icons were contributed by Christopher
+ Petrilli.
+</p>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node53.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node53.html">ADDENDUM: How to use</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/contents.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>Contents</title>
+<META NAME="description" CONTENT="Contents">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node2.html">
+<LINK REL="previous" HREF="zodb.html">
+<LINK REL="up" HREF="zodb.html">
+<LINK REL="next" HREF="node2.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node2.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node2.html">1 Introduction</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+<BR>
+<BR><H2><A NAME="SECTION000100000000000000000">
+Contents</A>
+</H2>
+<!--Table of Contents-->
+
+<UL>
+<LI><A href="contents.html">Contents</a>
+<LI><A href="node2.html">1 Introduction</a>
+<UL>
+<LI><A href="node3.html">1.1 What is the ZODB?</a>
+<LI><A href="node4.html">1.2 OODBs vs. Relational DBs</a>
+<LI><A href="node5.html">1.3 What is ZEO?</a>
+<LI><A href="node6.html">1.4 About this guide</a>
+<LI><A href="node7.html">1.5 Acknowledgements</a>
+</ul>
+<LI><A href="node8.html">2 ZODB Programming</a>
+<UL>
+<LI><A href="node9.html">2.1 Installing ZODB</a>
+<LI><A href="node12.html">2.2 How ZODB Works</a>
+<LI><A href="node13.html">2.3 Opening a ZODB</a>
+<LI><A href="node14.html">2.4 Writing a Persistent Class</a>
+<LI><A href="node15.html">2.5 Rules for Writing Persistent Classes</a>
+<LI><A href="node20.html">2.6 Writing Persistent Classes</a>
+</ul>
+<LI><A href="zeo.html">3 ZEO</a>
+<UL>
+<LI><A href="node23.html">3.1 How ZEO Works</a>
+<LI><A href="node24.html">3.2 Installing ZEO</a>
+<LI><A href="node27.html">3.3 Configuring and Running a ZEO Server</a>
+<LI><A href="node28.html">3.4 Testing the ZEO Installation</a>
+<LI><A href="node29.html">3.5 ZEO Programming Notes</a>
+<LI><A href="node30.html">3.6 Sample Application: chatter.py</a>
+</ul>
+<LI><A href="node31.html">4 Transactions and Versioning</a>
+<UL>
+<LI><A href="node32.html">4.1 Subtransactions</a>
+<LI><A href="node33.html">4.2 Undoing Changes</a>
+<LI><A href="node34.html">4.3 Versions</a>
+<LI><A href="node35.html">4.4 Multithreaded ZODB Programs</a>
+</ul>
+<LI><A href="node36.html">5 Related Modules</a>
+<UL>
+<LI><A href="node37.html">5.1 <tt class="module">ZODB.PersistentMapping</tt></a>
+<LI><A href="node38.html">5.2 <tt class="module">ZODB.PersistentList</tt></a>
+<LI><A href="node39.html">5.3 B-tree Modules</a>
+</ul>
+<LI><A href="node40.html">A. Resources</a>
+<LI><A href="node41.html">B. GNU Free Documentation License</a>
+<UL>
+<LI><A href="node42.html">Preamble</a>
+<LI><A href="node43.html">B..1 Applicability and Definitions</a>
+<LI><A href="node44.html">B..2 Verbatim Copying</a>
+<LI><A href="node45.html">B..3 Copying in Quantity</a>
+<LI><A href="node46.html">B..4 Modifications</a>
+<LI><A href="node47.html">B..5 Combining Documents</a>
+<LI><A href="node48.html">B..6 Collections of Documents</a>
+<LI><A href="node49.html">B..7 Aggregation With Independent Works</a>
+<LI><A href="node50.html">B..8 Translation</a>
+<LI><A href="node51.html">B..9 Termination</a>
+<LI><A href="node52.html">B..10 Future Revisions of This Licence</a>
+<LI><A href="node53.html">ADDENDUM: How to use this License for your documents</a>
+</ul>
+<LI><A href="about.html">About this document ...</a>
+</ul>
+<!--End of Table of Contents-->
+<P>
+©Copyright 2002 A.M. Kuchling.
+ Permission is granted to copy, distribute and/or modify this document
+ under the terms of the GNU Free Documentation License, Version 1.1
+ or any later version published by the Free Software Foundation;
+ with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
+ A copy of the license is included in the appendix entitled ``GNU
+ Free Documentation License''.
+
+<P>
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node2.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node2.html">1 Introduction</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/images.tex 1.1 => 1.2 ===
+\documentclass{howto}
+\RequirePackage{ifthen}
+
+
+
+\title{ZODB/ZEO Programming Guide}
+\release{0.03}
+\date{\today}
+
+\author{A.M.\ Kuchling}\authoraddress{akuchlin@mems-exchange.org}
+
+
+\usepackage[dvips]{color}
+
+
+\pagecolor[gray]{.7}
+
+\usepackage[latin1]{inputenc}
+
+
+
+\makeatletter
+
+\makeatletter
+\count@=\the\catcode`\_ \catcode`\_=8
+\newenvironment{tex2html_wrap}{}{}%
+\catcode`\<=12\catcode`\_=\count@
+\newcommand{\providedcommand}[1]{\expandafter\providecommand\csname #1\endcsname}%
+\newcommand{\renewedcommand}[1]{\expandafter\providecommand\csname #1\endcsname{}%
+ \expandafter\renewcommand\csname #1\endcsname}%
+\newcommand{\newedenvironment}[1]{\newenvironment{#1}{}{}\renewenvironment{#1}}%
+\let\newedcommand\renewedcommand
+\let\renewedenvironment\newedenvironment
+\makeatother
+\let\mathon=$
+\let\mathoff=$
+\ifx\AtBeginDocument\undefined \newcommand{\AtBeginDocument}[1]{}\fi
+\newbox\sizebox
+\setlength{\hoffset}{0pt}\setlength{\voffset}{0pt}
+\addtolength{\textheight}{\footskip}\setlength{\footskip}{0pt}
+\addtolength{\textheight}{\topmargin}\setlength{\topmargin}{0pt}
+\addtolength{\textheight}{\headheight}\setlength{\headheight}{0pt}
+\addtolength{\textheight}{\headsep}\setlength{\headsep}{0pt}
+\setlength{\textwidth}{349pt}
+\newwrite\lthtmlwrite
+\makeatletter
+\let\realnormalsize=\normalsize
+\global\topskip=2sp
+\def\preveqno{}\let\real@float=\@float \let\realend@float=\end@float
+\def\@float{\let\@savefreelist\@freelist\real@float}
+\def\liih@math{\ifmmode$\else\bad@math\fi}
+\def\end@float{\realend@float\global\let\@freelist\@savefreelist}
+\let\real@dbflt=\@dbflt \let\end@dblfloat=\end@float
+\let\@largefloatcheck=\relax
+\let\if@boxedmulticols=\iftrue
+\def\@dbflt{\let\@savefreelist\@freelist\real@dbflt}
+\def\adjustnormalsize{\def\normalsize{\mathsurround=0pt \realnormalsize
+ \parindent=0pt\abovedisplayskip=0pt\belowdisplayskip=0pt}%
+ \def\phantompar{\csname par\endcsname}\normalsize}%
+\def\lthtmltypeout#1{{\let\protect\string \immediate\write\lthtmlwrite{#1}}}%
+\newcommand\lthtmlhboxmathA{\adjustnormalsize\setbox\sizebox=\hbox\bgroup\kern.05em }%
+\newcommand\lthtmlhboxmathB{\adjustnormalsize\setbox\sizebox=\hbox to\hsize\bgroup\hfill }%
+\newcommand\lthtmlvboxmathA{\adjustnormalsize\setbox\sizebox=\vbox\bgroup %
+ \let\ifinner=\iffalse \let\)\liih@math }%
+\newcommand\lthtmlboxmathZ{\@next\next\@currlist{}{\def\next{\voidb@x}}%
+ \expandafter\box\next\egroup}%
+\newcommand\lthtmlmathtype[1]{\gdef\lthtmlmathenv{#1}}%
+\newcommand\lthtmllogmath{\lthtmltypeout{l2hSize %
+:\lthtmlmathenv:\the\ht\sizebox::\the\dp\sizebox::\the\wd\sizebox.\preveqno}}%
+\newcommand\lthtmlfigureA[1]{\let\@savefreelist\@freelist
+ \lthtmlmathtype{#1}\lthtmlvboxmathA}%
+\newcommand\lthtmlpictureA{\bgroup\catcode`\_=8 \lthtmlpictureB}%
+\newcommand\lthtmlpictureB[1]{\lthtmlmathtype{#1}\egroup
+ \let\@savefreelist\@freelist \lthtmlhboxmathB}%
+\newcommand\lthtmlpictureZ[1]{\hfill\lthtmlfigureZ}%
+\newcommand\lthtmlfigureZ{\lthtmlboxmathZ\lthtmllogmath\copy\sizebox
+ \global\let\@freelist\@savefreelist}%
+\newcommand\lthtmldisplayA{\bgroup\catcode`\_=8 \lthtmldisplayAi}%
+\newcommand\lthtmldisplayAi[1]{\lthtmlmathtype{#1}\egroup\lthtmlvboxmathA}%
+\newcommand\lthtmldisplayB[1]{\edef\preveqno{(\theequation)}%
+ \lthtmldisplayA{#1}\let\@eqnnum\relax}%
+\newcommand\lthtmldisplayZ{\lthtmlboxmathZ\lthtmllogmath\lthtmlsetmath}%
+\newcommand\lthtmlinlinemathA{\bgroup\catcode`\_=8 \lthtmlinlinemathB}
+\newcommand\lthtmlinlinemathB[1]{\lthtmlmathtype{#1}\egroup\lthtmlhboxmathA
+ \vrule height1.5ex width0pt }%
+\newcommand\lthtmlinlineA{\bgroup\catcode`\_=8 \lthtmlinlineB}%
+\newcommand\lthtmlinlineB[1]{\lthtmlmathtype{#1}\egroup\lthtmlhboxmathA}%
+\newcommand\lthtmlinlineZ{\egroup\expandafter\ifdim\dp\sizebox>0pt %
+ \expandafter\centerinlinemath\fi\lthtmllogmath\lthtmlsetinline}
+\newcommand\lthtmlinlinemathZ{\egroup\expandafter\ifdim\dp\sizebox>0pt %
+ \expandafter\centerinlinemath\fi\lthtmllogmath\lthtmlsetmath}
+\newcommand\lthtmlindisplaymathZ{\egroup %
+ \centerinlinemath\lthtmllogmath\lthtmlsetmath}
+\def\lthtmlsetinline{\hbox{\vrule width.1em \vtop{\vbox{%
+ \kern.1em\copy\sizebox}\ifdim\dp\sizebox>0pt\kern.1em\else\kern.3pt\fi
+ \ifdim\hsize>\wd\sizebox \hrule depth1pt\fi}}}
+\def\lthtmlsetmath{\hbox{\vrule width.1em\kern-.05em\vtop{\vbox{%
+ \kern.1em\kern0.8 pt\hbox{\hglue.17em\copy\sizebox\hglue0.8 pt}}\kern.3pt%
+ \ifdim\dp\sizebox>0pt\kern.1em\fi \kern0.8 pt%
+ \ifdim\hsize>\wd\sizebox \hrule depth1pt\fi}}}
+\def\centerinlinemath{%
+ \dimen1=\ifdim\ht\sizebox<\dp\sizebox \dp\sizebox\else\ht\sizebox\fi
+ \advance\dimen1by.5pt \vrule width0pt height\dimen1 depth\dimen1
+ \dp\sizebox=\dimen1\ht\sizebox=\dimen1\relax}
+
+\def\lthtmlcheckvsize{\ifdim\ht\sizebox<\vsize
+ \ifdim\wd\sizebox<\hsize\expandafter\hfill\fi \expandafter\vfill
+ \else\expandafter\vss\fi}%
+\providecommand{\selectlanguage}[1]{}%
+\makeatletter \tracingstats = 1
+
+
+\begin{document}
+\pagestyle{empty}\thispagestyle{empty}\lthtmltypeout{}%
+\lthtmltypeout{latex2htmlLength hsize=\the\hsize}\lthtmltypeout{}%
+\lthtmltypeout{latex2htmlLength vsize=\the\vsize}\lthtmltypeout{}%
+\lthtmltypeout{latex2htmlLength hoffset=\the\hoffset}\lthtmltypeout{}%
+\lthtmltypeout{latex2htmlLength voffset=\the\voffset}\lthtmltypeout{}%
+\lthtmltypeout{latex2htmlLength topmargin=\the\topmargin}\lthtmltypeout{}%
+\lthtmltypeout{latex2htmlLength topskip=\the\topskip}\lthtmltypeout{}%
+\lthtmltypeout{latex2htmlLength headheight=\the\headheight}\lthtmltypeout{}%
+\lthtmltypeout{latex2htmlLength headsep=\the\headsep}\lthtmltypeout{}%
+\lthtmltypeout{latex2htmlLength parskip=\the\parskip}\lthtmltypeout{}%
+\lthtmltypeout{latex2htmlLength oddsidemargin=\the\oddsidemargin}\lthtmltypeout{}%
+\makeatletter
+\if@twoside\lthtmltypeout{latex2htmlLength evensidemargin=\the\evensidemargin}%
+\else\lthtmltypeout{latex2htmlLength evensidemargin=\the\oddsidemargin}\fi%
+\lthtmltypeout{}%
+\makeatother
+\setcounter{page}{1}
+\onecolumn
+
+% !!! IMAGES START HERE !!!
+
+\stepcounter{section}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{section}
+\stepcounter{subsection}
+\stepcounter{subsubsection}
+\stepcounter{subsubsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsubsection}
+\stepcounter{subsubsection}
+\stepcounter{subsubsection}
+\stepcounter{subsubsection}
+\stepcounter{subsection}
+\stepcounter{subsubsection}
+\stepcounter{section}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsubsection}
+\stepcounter{subsubsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{section}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{section}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\appendix
+\stepcounter{section}
+\stepcounter{section}
+{\newpage\clearpage
+\lthtmlinlinemathA{tex2html_wrap_inline847}%
+$\copyright$%
+\lthtmlinlinemathZ
+\lthtmlcheckvsize\clearpage}
+
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+\stepcounter{subsection}
+
+\end{document}
=== StandaloneZODB/Doc/guide/zodb/img1.gif 1.1 => 1.2 ===
=== StandaloneZODB/Doc/guide/zodb/index.html 1.1 => 1.2 ===
+<html>
+<head>
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+<div class="titlepage">
+<center>
+<h1>ZODB/ZEO Programming Guide</h1>
+<p><b><font size="+2">A.M. Kuchling</font></b></p>
+<p>akuchlin@mems-exchange.org</p>
+<p><strong>Release 0.03</strong><br>
+<strong>February 8, 2002</strong></p>
+<p>
+</center>
+</div>
+
+<p><hr>
+<!--Table of Child-Links-->
+<A NAME="CHILD_LINKS"></a>
+
+<UL>
+<LI><A href="contents.html">Contents</a>
+<LI><A href="node2.html">1 Introduction</a>
+<UL>
+<LI><A href="node3.html">1.1 What is the ZODB?</a>
+<LI><A href="node4.html">1.2 OODBs vs. Relational DBs</a>
+<LI><A href="node5.html">1.3 What is ZEO?</a>
+<LI><A href="node6.html">1.4 About this guide</a>
+<LI><A href="node7.html">1.5 Acknowledgements</a>
+</ul>
+<LI><A href="node8.html">2 ZODB Programming</a>
+<UL>
+<LI><A href="node9.html">2.1 Installing ZODB</a>
+<UL>
+<LI><A href="node10.html">2.1.1 Requirements</a>
+<LI><A href="node11.html">2.1.2 Installing the Packages</a>
+</ul>
+<LI><A href="node12.html">2.2 How ZODB Works</a>
+<LI><A href="node13.html">2.3 Opening a ZODB</a>
+<LI><A href="node14.html">2.4 Writing a Persistent Class</a>
+<LI><A href="node15.html">2.5 Rules for Writing Persistent Classes</a>
+<UL>
+<LI><A href="node16.html">2.5.1 Modifying Mutable Objects</a>
+<LI><A href="node17.html">2.5.2 Some Special Methods Don't Work</a>
+<LI><A href="node18.html">2.5.3 Fixing <tt class="function">isinstance</tt> and <tt class="function">issubclass</tt></a>
+<LI><A href="node19.html">2.5.4 <tt class="method">__getattr__</tt>, <tt class="method">__delattr__</tt>, and <tt class="method">__setattr__</tt></a>
+</ul>
+<LI><A href="node20.html">2.6 Writing Persistent Classes</a>
+<UL>
+<LI><A href="node21.html">2.6.1 Changing Instance Attributes</a>
+</ul>
+</ul>
+<LI><A href="zeo.html">3 ZEO</a>
+<UL>
+<LI><A href="node23.html">3.1 How ZEO Works</a>
+<LI><A href="node24.html">3.2 Installing ZEO</a>
+<UL>
+<LI><A href="node25.html">3.2.1 Requirements</a>
+<LI><A href="node26.html">3.2.2 Installation</a>
+</ul>
+<LI><A href="node27.html">3.3 Configuring and Running a ZEO Server</a>
+<LI><A href="node28.html">3.4 Testing the ZEO Installation</a>
+<LI><A href="node29.html">3.5 ZEO Programming Notes</a>
+<LI><A href="node30.html">3.6 Sample Application: chatter.py</a>
+</ul>
+<LI><A href="node31.html">4 Transactions and Versioning</a>
+<UL>
+<LI><A href="node32.html">4.1 Subtransactions</a>
+<LI><A href="node33.html">4.2 Undoing Changes</a>
+<LI><A href="node34.html">4.3 Versions</a>
+<LI><A href="node35.html">4.4 Multithreaded ZODB Programs</a>
+</ul>
+<LI><A href="node36.html">5 Related Modules</a>
+<UL>
+<LI><A href="node37.html">5.1 <tt class="module">ZODB.PersistentMapping</tt></a>
+<LI><A href="node38.html">5.2 <tt class="module">ZODB.PersistentList</tt></a>
+<LI><A href="node39.html">5.3 B-tree Modules</a>
+</ul>
+<LI><A href="node40.html">A. Resources</a>
+<LI><A href="node41.html">B. GNU Free Documentation License</a>
+<UL>
+<LI><A href="node42.html">Preamble</a>
+<LI><A href="node43.html">B..1 Applicability and Definitions</a>
+<LI><A href="node44.html">B..2 Verbatim Copying</a>
+<LI><A href="node45.html">B..3 Copying in Quantity</a>
+<LI><A href="node46.html">B..4 Modifications</a>
+<LI><A href="node47.html">B..5 Combining Documents</a>
+<LI><A href="node48.html">B..6 Collections of Documents</a>
+<LI><A href="node49.html">B..7 Aggregation With Independent Works</a>
+<LI><A href="node50.html">B..8 Translation</a>
+<LI><A href="node51.html">B..9 Termination</a>
+<LI><A href="node52.html">B..10 Future Revisions of This Licence</a>
+<LI><A href="node53.html">ADDENDUM: How to use this License for your documents</a>
+</ul>
+<LI><A href="about.html">About this document ...</a>
+</ul>
+<!--End of Table of Child-Links-->
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><img src="/python/writing/icons/blank.gif"
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+<td><img src="/python/writing/icons/blank.gif"
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+</tr></table>
+<b class="navlabel">Next:</b> <a class="sectref" href="contents.html">Contents</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node10.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>2.1.1 Requirements</title>
+<META NAME="description" CONTENT="2.1.1 Requirements">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
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+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node9.html">2.1 Installing ZODB</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node9.html">2.1 Installing ZODB</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node11.html">2.1.2 Installing the Packages</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H3><A NAME="SECTION000311000000000000000">
+2.1.1 Requirements</A>
+</H3>
+
+<P>
+You'll need Python, of course; version 1.5.2 works with some fixes,
+and it also works with Python 2.0, which is what I primarily use.
+
+<P>
+The code is packaged using Distutils, the new distribution tools for
+Python introduced in Python 2.0. If you're using 1.5.2, first you'll
+have to get the latest Distutils release from the Distutils SIG page
+at <a class="url" href="http://www.python.org/sigs/distutils-sig/download.html">http://www.python.org/sigs/distutils-sig/download.html</a> and
+install it. This is simply a matter of untarring or unzipping the
+release package, and then running <code>python setup.py install</code>.
+
+<P>
+If you're using 1.5.2 and have installed previous versions of the
+Distutils, be sure to get the very latest version, since developing
+the ZODB distribution turned up some bugs along the way. If you
+encounter problems compiling <span class="file">ZODB/TimeStamp.c</span> or your compiler reports
+an error like ``Can't create build/temp.linux2/ExtensionClass.o: No
+such file or directory'', you need an updated version. Old versions of
+Distutils have two bugs which affect the setup scripts. First, for a
+long time the <code>define_macros</code> keyword in setup.py files didn't work due
+to a Distutils bug, so I hacked TimeStamp.c in earlier releases. The
+Distutils have since been fixed, and the hack became unnecessary, so I
+removed it. Second, the code that creates directories tries to be
+smart and caches them to save time by not trying to create a directory
+twice, but this code was broken in old versions.
+
+<P>
+You'll need a C compiler to build the packages, because there are
+various C extension modules. At the moment no one is making Windows
+binaries available, so you'll need a Windows development environment to use the
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node9.html"><img src="/python/writing/icons/previous.gif"
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+<b class="navlabel">Next:</b> <a class="sectref" HREF="node11.html">2.1.2 Installing the Packages</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
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+<head>
+<title>2.1.2 Installing the Packages</title>
+<META NAME="description" CONTENT="2.1.2 Installing the Packages">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
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+<tr>
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+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node10.html">2.1.1 Requirements</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node9.html">2.1 Installing ZODB</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node12.html">2.2 How ZODB Works</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H3><A NAME="SECTION000312000000000000000">
+2.1.2 Installing the Packages</A>
+</H3>
+
+<P>
+Download the ZODB tarball containing all the packages for both ZODB
+and ZEO from <a class="url" href="http://www.amk.ca/files/zodb/">http://www.amk.ca/files/zodb/</a>.
+
+<P>
+To build the packages, you must go into the individual directories and
+build and install them one by one. They should be built and installed
+in this order:
+
+<P>
+
+<OL>
+<LI><code>zodb-basic</code>
+</LI>
+<LI>ExtensionClass
+</LI>
+<LI>ZODB
+</LI>
+<LI><code>BTree</code> and <code>BTrees</code>
+</LI>
+<LI>ZEO
+</LI>
+</OL>
+
+<P>
+In particular, you must install ExtensionClass before building the
+ZODB package; otherwise, the compilation in the ZODB package will die
+complaining that it can't find ExtensionClass.h. You can manually
+hack the #include path to make it work without installing
+ExtensionClass first, but that's a bit hackish.
+
+<P>
+If you encounter any problems, please let me know at
+<span class="email">akuchlin@mems-exchange.org</span>.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node10.html"><img src="/python/writing/icons/previous.gif"
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+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
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+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
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+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
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+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node10.html">2.1.1 Requirements</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node9.html">2.1 Installing ZODB</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node12.html">2.2 How ZODB Works</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node12.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>2.2 How ZODB Works</title>
+<META NAME="description" CONTENT="2.2 How ZODB Works">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node13.html">
+<LINK REL="previous" HREF="node9.html">
+<LINK REL="up" HREF="node8.html">
+<LINK REL="next" HREF="node13.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node11.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
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+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node11.html">2.1.2 Installing the Packages</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node13.html">2.3 Opening a ZODB</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000320000000000000000">
+2.2 How ZODB Works</A>
+</H2>
+
+<P>
+The ZODB is conceptually simple. Python classes subclass a
+<tt class="class">Persistent</tt> class to become ZODB-aware.
+Instances of persistent objects are brought in from a permanent
+storage medium, such as a disk file, when the program needs them, and
+remain cached in RAM. The ZODB traps modifications to objects, so
+that when a statement such as <code>obj.size = 1</code> is executed, the
+modified object is marked as ``dirty''. On request, any dirty objects
+are written out to permanent storage; this is called committing a
+transaction. Transactions can also be aborted or rolled back, which
+results in any changes being discarded, dirty objects reverting to
+their initial state before the transaction began.
+
+<P>
+The term ``transaction'' has a specific technical meaning in computer
+science. It's extremely important that the contents of a database
+don't get corrupted by software or hardware crashes, and most database
+software offers protection against such corruption by supporting four
+useful properties, Atomicity, Consistency, Isolation, and Durability.
+In computer science jargon these four terms are collectively dubbed
+the ACID properties, forming an acronym from their names. The
+definitions of the ACID properties are:
+
+<P>
+<DL COMPACT>
+<DT>Atomicity</DT>
+<DD>means that any changes to data made during a transaction
+are all-or-nothing. Either all the changes are applied, or none of
+them are. If a program makes a bunch of modifications and then
+crashes, the database won't be partially modified, potentially leaving
+the data in an inconsistent state; instead all the changes will be
+forgotten. That's bad, but it's better than having a
+partially-applied modification put the database into an inconsistent
+state.
+
+<P>
+</DD>
+<DT>Consistency</DT>
+<DD>means that the data cannot be placed into a
+logically invalid state; sanity checks can be written and enforced.
+Usually this is done by defining a database schema, and requiring the
+data always matches the schema. For example, this might enforce that
+the <code>order_number</code> attribute is always an integer, and not a
+string, tuple, or other object.
+
+<P>
+</DD>
+<DT>Isolation</DT>
+<DD>means that two programs or threads running in two
+ different transactions cannot see each other's changes until they
+ commit their transactions.
+
+<P>
+</DD>
+<DT>Durability</DT>
+<DD>means that once a transaction has been committed,
+a subsequent crash will not cause any data to be lost or corrupted.
+
+<P>
+</DD>
+</DL>
+
+<P>
+The ZODB provides 3 of the ACID properties. Only Consistency is not
+supported; the ZODB has no notion of a database schema, and therefore
+has no way of enforcing consistency with a schema.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node11.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
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+<td><A HREF="node8.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
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+<td><A HREF="node13.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node11.html">2.1.2 Installing the Packages</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node13.html">2.3 Opening a ZODB</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node13.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>2.3 Opening a ZODB</title>
+<META NAME="description" CONTENT="2.3 Opening a ZODB">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
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+<LINK REL="previous" HREF="node12.html">
+<LINK REL="up" HREF="node8.html">
+<LINK REL="next" HREF="node14.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node12.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
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+<td><A HREF="node14.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node12.html">2.2 How ZODB Works</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node14.html">2.4 Writing a Persistent</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000330000000000000000">
+2.3 Opening a ZODB</A>
+</H2>
+
+<P>
+There are 3 main interfaces supplied by the ZODB:
+<tt class="class">Storage</tt>, <tt class="class">DB</tt>, and <tt class="class">Connection</tt> classes. The
+<tt class="class">DB</tt> and <tt class="class">Connection</tt> interfaces both have single
+implementations, but there are several different classes that
+implement the <tt class="class">Storage</tt> interface.
+
+<P>
+
+<UL>
+<LI><tt class="class">Storage</tt> classes are the lowest layer, and handle
+ storing and retrieving objects from some form of long-term storage.
+ A few different types of Storage have been written, such as
+ <tt class="class">FileStorage</tt>, which uses regular disk files, and
+ <tt class="class">BerkeleyStorage</tt>, which uses Sleepycat Software's BerkeleyDB
+ database. You could write a new Storage that stored objects in a
+ relational database or Metakit file, for example, if that would
+ better suit your application. Two example storages,
+ <tt class="class">DemoStorage</tt> and <tt class="class">MappingStorage</tt>, are available to use
+ as models if you want to write a new Storage.
+
+<P>
+</LI>
+<LI>The <tt class="class">DB</tt> class sits on top of a storage, and mediates the
+ interaction between several connections. One <tt class="class">DB</tt> instance is
+ created per process.
+
+<P>
+</LI>
+<LI>Finally, the <tt class="class">Connection</tt> class caches objects, and moves
+ them into and out of object storage. A multi-threaded program can
+ open a separate <tt class="class">Connection</tt> instance for each thread.
+ Different threads can then modify objects and commit their
+ modifications independently.
+
+<P>
+</LI>
+</UL>
+
+<P>
+Preparing to use a ZODB requires 3 steps: you have to open the
+<tt class="class">Storage</tt>, then create a <tt class="class">DB</tt> instance that uses the <tt class="class">Storage</tt>, and then get
+a <tt class="class">Connection</tt> from the <tt class="class">DB instance</tt>. All this is only a few lines of
+code:
+
+<P>
+<dl><dd><pre class="verbatim">
+from ZODB import FileStorage, DB
+
+storage = FileStorage.FileStorage('/tmp/test-filestorage.fs')
+db = DB(storage)
+conn = db.open()
+</pre></dl>
+
+<P>
+Note that you can use a completely different data storage mechanism by
+changing the first line that opens a <tt class="class">Storage</tt>; the above example uses a
+<tt class="class">FileStorage</tt>. In section <A href="zeo.html#zeo">3</A>, ``How ZEO Works'',
+you'll see how ZEO uses this flexibility to good effect.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node12.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
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+<td><A HREF="node8.html"><img src="/python/writing/icons/up.gif"
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+<td><A HREF="node14.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node12.html">2.2 How ZODB Works</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node14.html">2.4 Writing a Persistent</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node14.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>2.4 Writing a Persistent Class</title>
+<META NAME="description" CONTENT="2.4 Writing a Persistent Class">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
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+
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+<LINK REL="previous" HREF="node13.html">
+<LINK REL="up" HREF="node8.html">
+<LINK REL="next" HREF="node15.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node13.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node8.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node15.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node13.html">2.3 Opening a ZODB</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node15.html">2.5 Rules for Writing</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000340000000000000000">
+2.4 Writing a Persistent Class</A>
+</H2>
+
+<P>
+Making a Python class persistent is quite simple; it simply needs to
+subclass from the <tt class="class">Persistent</tt> class, as shown in this example:
+
+<P>
+<dl><dd><pre class="verbatim">
+import ZODB
+from Persistence import Persistent
+
+class User(Persistent):
+ pass
+</pre></dl>
+
+<P>
+The apparently unnecessary <code>import ZODB</code> statement is
+needed for the following <code>from...import</code> statement to work
+correctly, since the ZODB code does some magical tricks with
+importing.
+
+<P>
+For simplicity, in the examples the <tt class="class">User</tt> class will
+simply be used as a holder for a bunch of attributes. Normally the
+class would define various methods that add functionality, but that
+has no impact on the ZODB's treatment of the class.
+
+<P>
+The ZODB uses persistence by reachability; starting from a set of root
+objects, all the attributes of those objects are made persistent,
+whether they're simple Python data types or class instances. There's
+no method to explicitly store objects in a ZODB database; simply
+assign them as an attribute of an object, or store them in a mapping,
+that's already in the database. This chain of containment must
+eventually reach back to the root object of the database.
+
+<P>
+As an example, we'll create a simple database of users that allows
+retrieving a <tt class="class">User</tt> object given the user's ID. First, we
+retrieve the primary root object of the ZODB using the <tt class="method">root()</tt>
+method of the <tt class="class">Connection</tt> instance. The root object behaves
+like a Python dictionary, so you can just add a new key/value pair for
+your application's root object. We'll insert a <tt class="class">BTree</tt> object
+that will contain all the <tt class="class">User</tt> objects. (The
+<tt class="class">BTree</tt> module is also included as part of Zope.)
+
+<P>
+<dl><dd><pre class="verbatim">
+dbroot = conn.root()
+
+# Ensure that a 'userdb' key is present
+# in the root
+if not dbroot.has_key('userdb'):
+ import BTree
+ dbroot['userdb'] = BTree.BTree()
+
+userdb = dbroot['userdb']
+</pre></dl>
+
+<P>
+Inserting a new user is simple: create the <tt class="class">User</tt> object, fill
+it with data, insert it into the <tt class="class">BTree</tt> instance, and commit
+this transaction.
+
+<P>
+<dl><dd><pre class="verbatim"># Create new User instance
+newuser = User()
+
+# Add whatever attributes you want to track
+newuser.id = 'amk'
+newuser.first_name = 'Andrew' ; newuser.last_name = 'Kuchling'
+...
+
+# Add object to the BTree, keyed on the ID
+userdb[newuser.id] = newuser
+
+# Commit the change
+get_transaction().commit()
+</pre></dl>
+
+<P>
+When you import the ZODB package, it adds a new function,
+<tt class="function">get_transaction()</tt>, to Python's collection of built-in
+functions. <tt class="function">get_transaction()</tt> returns a <tt class="class">Transaction</tt>
+object, which has two important methods: <tt class="method">commit()</tt> and
+<tt class="method">abort()</tt>. <tt class="method">commit()</tt> writes any modified objects
+to disk, making the changes permanent, while <tt class="method">abort()</tt> rolls
+back any changes that have been made, restoring the original state of
+the objects. If you're familiar with database transactional
+semantics, this is all what you'd expect.
+
+<P>
+Because the integration with Python is so complete, it's a lot like
+having transactional semantics for your program's variables, and you
+can experiment with transactions at the Python interpreter's prompt:
+
+<P>
+<dl><dd><pre class="verbatim">>>> newuser
+<User instance at 81b1f40>
+>>> newuser.first_name # Print initial value
+'Andrew'
+>>> newuser.first_name = 'Bob' # Change first name
+>>> newuser.first_name # Verify the change
+'Bob'
+>>> get_transaction().abort() # Abort transaction
+>>> newuser.first_name # The value has changed back
+'Andrew'
+</pre></dl>
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node13.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node8.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
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+<td><A HREF="node15.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
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+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node13.html">2.3 Opening a ZODB</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node15.html">2.5 Rules for Writing</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node15.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>2.5 Rules for Writing Persistent Classes</title>
+<META NAME="description" CONTENT="2.5 Rules for Writing Persistent Classes">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
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+<meta http-equiv="Content-Type" content="text/html; charset=">
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+
+<LINK REL="next" HREF="node20.html">
+<LINK REL="previous" HREF="node14.html">
+<LINK REL="up" HREF="node8.html">
+<LINK REL="next" HREF="node16.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node14.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node8.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
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+<td><A HREF="node16.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node14.html">2.4 Writing a Persistent</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node16.html">2.5.1 Modifying Mutable Objects</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000350000000000000000">
+2.5 Rules for Writing Persistent Classes</A>
+</H2>
+
+<P>
+Practically all persistent languages impose some restrictions on
+programming style, warning against constructs they can't handle or
+adding subtle semantic changes, and the ZODB is no exception.
+Happily, the ZODB's restrictions are fairly simple to understand, and
+in practice it isn't too painful to work around them.
+
+<P>
+The summary of rules is as follows:
+
+<P>
+
+<UL>
+<LI>If you modify a mutable object that's the value of an object's
+attribute, the ZODB can't catch that, and won't mark the object as
+dirty.
+The solution is to either set the dirty bit yourself when you modify
+mutable objects, or use a wrapper for Python's lists and dictionaries
+(<tt class="class">PersistentList</tt>,
+<tt class="class">PersistentMapping</tt>)
+that will set the dirty bit properly.
+
+<P>
+</LI>
+<LI>Certain of Python's special methods don't work when they're
+defined on ExtensionClasses. The most important ones are the
+<tt class="method">__cmp__</tt> method, and the reversed versions of binary
+arithmetic operations: <tt class="method">__radd__</tt>, <tt class="method">__rsub__</tt>, and so
+forth.
+
+<P>
+</LI>
+<LI>Python's built-in <tt class="function">isinstance()</tt> and <tt class="function">issubclass()</tt>
+functions don't work properly on ExtensionClasses. Solution: use
+custom <tt class="function">isinstance()</tt> and <tt class="function">issubclass()</tt> functions
+that handle ExtensionClasses correctly.
+
+<P>
+</LI>
+<LI>Recent versions of the ZODB allow writing a class with
+<tt class="method">__setattr__</tt> , <tt class="method">__getattr__</tt>, or <tt class="method">__delattr__</tt> methods. (Older versions didn't support this at all.)
+If you write such a <tt class="method">__setattr__</tt> or <tt class="method">__delattr__</tt> method,
+its code has to set the dirty bit manually,
+
+<P>
+</LI>
+</UL>
+
+<P>
+Let's look at each of these rules in detail.
+
+<P>
+
+<p><hr>
+<!--Table of Child-Links-->
+<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></a>
+
+<UL>
+<LI><A href="node16.html">2.5.1 Modifying Mutable Objects</a>
+<LI><A href="node17.html">2.5.2 Some Special Methods Don't Work</a>
+<LI><A href="node18.html">2.5.3 Fixing <tt class="function">isinstance</tt> and <tt class="function">issubclass</tt></a>
+<LI><A href="node19.html">2.5.4 <tt class="method">__getattr__</tt>, <tt class="method">__delattr__</tt>, and <tt class="method">__setattr__</tt></a>
+</ul>
+<!--End of Table of Child-Links-->
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node14.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
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+<td><A HREF="node8.html"><img src="/python/writing/icons/up.gif"
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+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
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+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node14.html">2.4 Writing a Persistent</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node16.html">2.5.1 Modifying Mutable Objects</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node16.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>2.5.1 Modifying Mutable Objects</title>
+<META NAME="description" CONTENT="2.5.1 Modifying Mutable Objects">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
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+<link rel="first" href="zodb.html">
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+
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+<LINK REL="previous" HREF="node15.html">
+<LINK REL="up" HREF="node15.html">
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+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node15.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
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+ border="0" height="32"
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+<td><A HREF="node17.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node15.html">2.5 Rules for Writing</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node15.html">2.5 Rules for Writing</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node17.html">2.5.2 Some Special Methods</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H3><A NAME="SECTION000351000000000000000">
+2.5.1 Modifying Mutable Objects</A>
+</H3>
+
+<P>
+The ZODB uses various Python hooks to catch attribute accesses, and
+can trap most of the ways of modifying an object, but not all of them.
+If you modify a <tt class="class">User</tt> object by assigning to one of its
+attributes, as in <code>userobj.first_name = 'Andrew'</code>, the ZODB will
+mark the object as having been changed, and it'll be written out on
+the following <tt class="method">commit()</tt>.
+
+<P>
+The most common idiom that <i>isn't</i> caught by the ZODB is
+mutating a list or dictionary. If <tt class="class">User</tt> objects have a
+attribute named <code>friends</code> containing a list, calling
+<code>userobj.friends.append(otherUser)</code> doesn't mark
+<code>userobj</code> as modified; from the ZODB's point of
+view, <code>userobj.friends</code> was only read, and its value, which
+happened to be an ordinary Python list, was returned. The ZODB isn't
+aware that the object returned was subsequently modified.
+
+<P>
+This is one of the few quirks you'll have to remember when using the
+ZODB; if you modify a mutable attribute of an object in place, you
+have to manually mark the object as having been modified by setting
+its dirty bit to true. This is done by setting the
+<tt class="member">_p_changed</tt> attribute of the object to true:
+
+<P>
+<dl><dd><pre class="verbatim">
+userobj.friends.append(otherUser)
+userobj._p_changed = 1
+</pre></dl>
+
+<P>
+An obsolete way of doing this that's still supported is calling the
+<tt class="method">__changed__()</tt> method instead, but setting <tt class="member">_p_changed</tt>
+is the preferred way.
+
+<P>
+You can hide the implementation detail of having to mark objects as
+dirty by designing your class's API to not use direct attribute
+access; instead, you can use the Java-style approach of accessor
+methods for everything, and then set the dirty bit within the accessor
+method. For example, you might forbid accessing the <code>friends</code>
+attribute directly, and add a <tt class="method">get_friend_list()</tt> accessor and
+an <tt class="method">add_friend()</tt> modifier method to the class. <tt class="method">add_friend()</tt>
+would then look like this:
+
+<P>
+<dl><dd><pre class="verbatim">
+ def add_friend(self, friend):
+ self.friends.append(otherUser)
+ self._p_changed = 1
+</pre></dl>
+
+<P>
+Alternatively, you could use a ZODB-aware list or mapping type that
+handles the dirty bit for you. The ZODB comes with a
+<tt class="class">PersistentMapping</tt> class, and I've contributed a
+<tt class="class">PersistentList</tt> class that's included in my ZODB distribution,
+and may make it into a future upstream release of Zope.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node15.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node15.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
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+<td><A HREF="node17.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node15.html">2.5 Rules for Writing</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node15.html">2.5 Rules for Writing</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node17.html">2.5.2 Some Special Methods</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node17.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>2.5.2 Some Special Methods Don't Work</title>
+<META NAME="description" CONTENT="2.5.2 Some Special Methods Don't Work">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
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+<LINK REL="previous" HREF="node16.html">
+<LINK REL="up" HREF="node15.html">
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+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node16.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node15.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node18.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node16.html">2.5.1 Modifying Mutable Objects</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node15.html">2.5 Rules for Writing</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node18.html">2.5.3 Fixing isinstance and</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H3><A NAME="SECTION000352000000000000000">
+2.5.2 Some Special Methods Don't Work</A>
+</H3>
+
+<P>
+Don't bother defining certain special methods on
+ExtensionClasses, because they won't work. Most notably, the
+<tt class="method">__cmp__</tt> method on an ExtensionClass will never be called.
+Neither will the reversed versions of binary arithmetic operations,
+such as <tt class="method">__radd__</tt> and <tt class="method">__rsub__</tt>.
+
+<P>
+This is a moderately annoying limitation. It means that the
+<tt class="class">PersistentList</tt> class can't implement comparisons with regular
+sequence objects, and therefore statements such as
+<code>if perslist==[]</code> don't do what you expect; instead of performing the correct
+comparison, they return some arbitrary fixed result, so the <code>if</code>
+statement will always be true or always be false. There is no good
+solution to this problem at the moment, so all you can do is design
+class interfaces that don't need to overload
+<tt class="method">__cmp__</tt> or the <tt class="method">__r*__</tt> methods.
+
+<P>
+This limitation is mostly Python's fault. As of Python 2.1, the most
+recent version at this writing, the code which handles comparing two
+Python objects contains a hard-wired check for objects that are class
+instances, which means that <code>type(obj) == types.InstanceType</code>.
+The code inside the Python interpreter looks like this:
+
+<P>
+<dl><dd><pre class="verbatim">
+/* Code to compare objects v and w */
+if (PyInstance_Check(v) || PyInstance_Check(w))
+ return PyInstance_DoBinOp(v, w, "__cmp__", "__rcmp__", do_cmp);
+/* Do usual Python comparison of v,w */
+c = PyObject_Compare(v, w);
+</pre></dl>
+
+<P>
+While ExtensionClasses try to behave as much like regular Python
+instances as possible, they are still not instances, and
+<tt class="function">type()</tt> doesn't return the <code>InstanceType</code> object, so
+no attempt is ever made to call <tt class="method">__cmp__</tt>. Perhaps Python 2.2
+will repair this.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node16.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node15.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node18.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node16.html">2.5.1 Modifying Mutable Objects</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node15.html">2.5 Rules for Writing</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node18.html">2.5.3 Fixing isinstance and</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node18.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>2.5.3 Fixing isinstance and issubclass</title>
+<META NAME="description" CONTENT="2.5.3 Fixing isinstance and issubclass">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node19.html">
+<LINK REL="previous" HREF="node17.html">
+<LINK REL="up" HREF="node15.html">
+<LINK REL="next" HREF="node19.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node17.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
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+ border="0" height="32"
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+<td><A HREF="node19.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node17.html">2.5.2 Some Special Methods</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node15.html">2.5 Rules for Writing</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node19.html">2.5.4 __getattr__, __delattr__, and</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H3><A NAME="SECTION000353000000000000000">
+2.5.3 Fixing <tt class="function">isinstance</tt> and <tt class="function">issubclass</tt></A>
+</H3>
+
+<P>
+Python's built-in functions
+<tt class="function">isinstance()</tt> and <tt class="function">issubclass</tt> don't
+work on ExtensionClass instances, for much the same reason that
+<tt class="method">__cmp__</tt> is never called; in some bits of the Python core code,
+branches are taken only if an object is of the <tt class="class">InstanceType</tt>
+type, and this can never be true for an ExtensionClass instance.
+Python 2.1 tried to fix this, and changed these functions slightly in
+an effort to make them work for ExtensionClasses; unfortunately, the
+changes didn't work.
+
+<P>
+The solution is to use customized versions of these functions that
+handle ExtensionClasses specially and fall back to the built-in
+version otherwise. Here are the versions we've written at the MEMS Exchange:
+
+<P>
+<dl><dd><pre class="verbatim">
+# The built-in 'isinstance()' and 'issubclass()' won't work on
+# ExtensionClasses, so you have to use the versions supplied here.
+# (But those versions work fine on regular instances and classes too,
+# so you should *always* use them.)
+
+def issubclass (class1, class2):
+ """A version of 'issubclass' that works with extension classes
+ as well as regular Python classes.
+ """
+
+ # Both class objects are regular Python classes, so use the
+ # built-in 'issubclass()'.
+ if type(class1) is ClassType and type(class2) is ClassType:
+ return __builtin__.issubclass(class1, class2)
+
+ # Both so-called class objects have a '__bases__' attribute: ie.,
+ # they aren't regular Python classes, but they sure look like them.
+ # Assume they are extension classes and reimplement what the builtin
+ # 'issubclass()' does behind the scenes.
+ elif hasattr(class1, '__bases__') and hasattr(class2, '__bases__'):
+ # XXX it appears that "ec.__class__ is type(ec)" for an
+ # extension class 'ec': could we/should we use this as an
+ # additional check for extension classes?
+
+ # Breadth-first traversal of class1's superclass tree. Order
+ # doesn't matter because we're just looking for a "yes/no"
+ # answer from the tree; if we were trying to resolve a name,
+ # order would be important!
+ stack = [class1]
+ while stack:
+ if stack[0] is class2:
+ return 1
+ stack.extend(list(stack[0].__bases__))
+ del stack[0]
+ else:
+ return 0
+
+ # Not a regular class, not an extension class: blow up for consistency
+ # with builtin 'issubclass()"
+ else:
+ raise TypeError, "arguments must be class or ExtensionClass objects"
+
+# issubclass ()
+
+def isinstance (object, klass):
+ """A version of 'isinstance' that works with extension classes
+ as well as regular Python classes."""
+
+ if type(klass) is TypeType:
+ return __builtin__.isinstance(object, klass)
+ elif hasattr(object, '__class__'):
+ return issubclass(object.__class__, klass)
+ else:
+ return 0
+</pre></dl>
+
+<P>
+I'd recommend putting these functions in a module that always gets
+imported. The convention on my work project is to put them in
+<span class="file">mems/lib/base.py</span>, which contains various fundamental classes
+and functions for our system, and access them like this:
+
+<P>
+<dl><dd><pre class="verbatim">
+from mems.lib import base
+...
+if base.isinstance(object, Class): ...
+</pre></dl>
+
+<P>
+Don't insert the modified functions into Python's
+<tt class="module">__builtin__</tt> module, or import just the
+<tt class="function">isinstance()</tt> and <tt class="function">issubclass</tt> functions.
+If you consistently use <tt class="function">base.isinstance()</tt>, then forgetting
+to import the <tt class="module">base</tt> module will result in a
+<tt class="exception">NameError</tt> exception. In the
+case of a forgotten import, calling the functions directly would use
+Python's built-in versions, leading to subtle bugs that might not be
+noticed for some time.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node17.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node15.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node19.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node17.html">2.5.2 Some Special Methods</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node15.html">2.5 Rules for Writing</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node19.html">2.5.4 __getattr__, __delattr__, and</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node19.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>2.5.4 __getattr__, __delattr__, and __setattr__</title>
+<META NAME="description" CONTENT="2.5.4 __getattr__, __delattr__, and __setattr__">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
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+<meta http-equiv="Content-Type" content="text/html; charset=">
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+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="previous" HREF="node18.html">
+<LINK REL="up" HREF="node15.html">
+<LINK REL="next" HREF="node20.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node18.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
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+ border="0" height="32"
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+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node18.html">2.5.3 Fixing isinstance and</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node15.html">2.5 Rules for Writing</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node20.html">2.6 Writing Persistent Classes</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H3><A NAME="SECTION000354000000000000000">
+2.5.4 <tt class="method">__getattr__</tt>, <tt class="method">__delattr__</tt>, and <tt class="method">__setattr__</tt></A>
+</H3>
+
+<P>
+Recent versions of ZODB allow writing persistent classes that have
+<tt class="method">__getattr__</tt>, <tt class="method">__delattr__</tt>, or <tt class="method">__setattr__</tt>
+methods. The one minor complication is that the machinery for
+automatically detecting changes to the object is disabled while the
+<tt class="method">__getattr__</tt>, <tt class="method">__delattr__</tt>, or <tt class="method">__setattr__</tt>
+method is executing. This means that if the object is modified, the
+object should be marked as dirty by setting the object's
+<tt class="member">_p_changed</tt> method to true.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node18.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node15.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node20.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node18.html">2.5.3 Fixing isinstance and</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node15.html">2.5 Rules for Writing</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node20.html">2.6 Writing Persistent Classes</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node2.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>1 Introduction</title>
+<META NAME="description" CONTENT="1 Introduction">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node8.html">
+<LINK REL="previous" href="contents.html">
+<LINK REL="up" HREF="zodb.html">
+<LINK REL="next" HREF="node3.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A href="contents.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node3.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" href="contents.html">Contents</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node3.html">1.1 What is the</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H1><A NAME="SECTION000200000000000000000">
+1 Introduction</A>
+</H1>
+
+<P>
+This guide explains how to write Python programs that use the Z Object
+Database (ZODB) and Zope Enterprise Objects (ZEO). The latest version
+of the guide is always available at
+<a class="url" href="http://www.amk.ca/zodb/guide/">http://www.amk.ca/zodb/guide/</a>.
+
+<P>
+
+<p><hr>
+<!--Table of Child-Links-->
+<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></a>
+
+<UL>
+<LI><A href="node3.html">1.1 What is the ZODB?</a>
+<LI><A href="node4.html">1.2 OODBs vs. Relational DBs</a>
+<LI><A href="node5.html">1.3 What is ZEO?</a>
+<LI><A href="node6.html">1.4 About this guide</a>
+<LI><A href="node7.html">1.5 Acknowledgements</a>
+</ul>
+<!--End of Table of Child-Links-->
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A href="contents.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node3.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" href="contents.html">Contents</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node3.html">1.1 What is the</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node20.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>2.6 Writing Persistent Classes</title>
+<META NAME="description" CONTENT="2.6 Writing Persistent Classes">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="previous" HREF="node15.html">
+<LINK REL="up" HREF="node8.html">
+<LINK REL="next" HREF="node21.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node19.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node8.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node21.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node19.html">2.5.4 __getattr__, __delattr__, and</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node21.html">2.6.1 Changing Instance Attributes</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000360000000000000000">
+2.6 Writing Persistent Classes</A>
+</H2>
+
+<P>
+Now that we've looked at the basics of programming using the ZODB,
+we'll turn to some more subtle tasks that are likely to come up for
+anyone using the ZODB in a production system.
+
+<P>
+
+<p><hr>
+<!--Table of Child-Links-->
+<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></a>
+
+<UL>
+<LI><A href="node21.html">2.6.1 Changing Instance Attributes</a>
+</ul>
+<!--End of Table of Child-Links-->
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node19.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node8.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node21.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node19.html">2.5.4 __getattr__, __delattr__, and</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node21.html">2.6.1 Changing Instance Attributes</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node21.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>2.6.1 Changing Instance Attributes</title>
+<META NAME="description" CONTENT="2.6.1 Changing Instance Attributes">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="previous" HREF="node20.html">
+<LINK REL="up" HREF="node20.html">
+<LINK REL="next" href="zeo.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node20.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node20.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A href="zeo.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node20.html">2.6 Writing Persistent Classes</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node20.html">2.6 Writing Persistent Classes</A>
+<b class="navlabel">Next:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H3><A NAME="SECTION000361000000000000000">
+2.6.1 Changing Instance Attributes</A>
+</H3>
+
+<P>
+Ideally, before making a class persistent you would get its interface
+right the first time, so that no attributes would ever need to be
+added, removed, or have their interpretation change over time. It's a
+worthy goal, but also an impractical one unless you're gifted with
+perfect knowledge of the future. Such unnatural foresight can't be
+required of any person, so you therefore have to be prepared to handle
+such structural changes gracefully. In object-oriented database
+terminology, this is a schema update. The ZODB doesn't have an actual
+schema specification, but you're changing the software's expectations
+of the data contained by an object, so you're implicitly changing the
+schema.
+
+<P>
+One way to handle such a change is to write a one-time conversion
+program that will loop over every single object in the database and
+update them to match the new schema. This can be easy if your network
+of object references is quite structured, making it easy to find all
+the instances of the class being modified. For example, if all
+<tt class="class">User</tt> objects can be found inside a single dictionary or
+B-tree, then it would be a simple matter to loop over every
+<tt class="class">User</tt> instance with a <tt class="keyword">for</tt> statement.
+This is more difficult if your object graph is less structured; if
+<tt class="class">User</tt> objects can be found as attributes of any number of
+different class instances, then there's no longer any easy way to find
+them all, short of writing a generalized object traversal function
+that would walk over every single object in a ZODB, checking each one
+to see if it's an instance of <tt class="class">User</tt>.
+<A NAME="tex2html1"
+ HREF="#foot287"><SUP>1</SUP></A>Some OODBs support a feature called extents, which allow quickly
+finding all the instances of a given class, no matter where they are
+in the object graph; unfortunately the ZODB doesn't offer extents as a
+feature.
+
+<P>
+XXX Rest of section not written yet: __getstate__/__setstate__
+
+<P>
+<BR><HR><H4>Footnotes</H4>
+<DL>
+<DT><A NAME="foot287">...User.
+</A><A NAME="foot287"
+ HREF="node21.html#tex2html1"><SUP>1</SUP></A>
+<DD>XXX is there a convenience method for walking the object graph hiding
+somewhere inside DC's code? Should there be a utility method for
+doing this? Should I write one and include it in this section?
+
+</DL>
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node20.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node20.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A href="zeo.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node20.html">2.6 Writing Persistent Classes</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node20.html">2.6 Writing Persistent Classes</A>
+<b class="navlabel">Next:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node23.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>3.1 How ZEO Works</title>
+<META NAME="description" CONTENT="3.1 How ZEO Works">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node24.html">
+<LINK REL="previous" href="zeo.html">
+<LINK REL="up" href="zeo.html">
+<LINK REL="next" HREF="node24.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A href="zeo.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A href="zeo.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node24.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<b class="navlabel">Up:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node24.html">3.2 Installing ZEO</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000410000000000000000">
+3.1 How ZEO Works</A>
+</H2>
+
+<P>
+The ZODB, as I've described it so far, can only be used within a
+single Python process (though perhaps with multiple threads). ZEO,
+Zope Enterprise Objects, extends the ZODB machinery to provide access
+to objects over a network. The name "Zope Enterprise Objects" is a
+bit misleading; ZEO can be used to store Python objects and access
+them in a distributed fashion without Zope ever entering the picture.
+The combination of ZEO and ZODB is essentially a Python-specific
+object database.
+
+<P>
+ZEO consists of about 1400 lines of Python code. The code is
+relatively small because it contains only code for a TCP/IP server,
+and for a new type of Storage, <tt class="class">ClientStorage</tt>.
+<tt class="class">ClientStorage</tt> doesn't use disk files at all; it simply
+makes remote procedure calls to the server, which then passes them on
+a regular <tt class="class">Storage</tt> class such as <tt class="class">FileStorage</tt>. The
+following diagram lays out the system:
+
+<P>
+XXX insert diagram here later
+
+<P>
+Any number of processes can create a <tt class="class">ClientStorage</tt>
+instance, and any number of threads in each process can be using that
+instance. <tt class="class">ClientStorage</tt> aggressively caches objects
+locally, so in order to avoid using stale data, the ZEO server sends
+an invalidate message to all the connected <tt class="class">ClientStorage</tt>
+instances on every write operation. The invalidate message contains
+the object ID for each object that's been modified, letting the
+<tt class="class">ClientStorage</tt> instances delete the old data for the
+given object from their caches.
+
+<P>
+This design decision has some consequences you should be aware of.
+First, while ZEO isn't tied to Zope, it was first written for use with
+Zope, which stores HTML, images, and program code in the database. As
+a result, reads from the database are <i>far</i> more frequent than
+writes, and ZEO is therefore better suited for read-intensive
+applications. If every <tt class="class">ClientStorage</tt> is writing to the
+database all the time, this will result in a storm of invalidate
+messages being sent, and this might take up more processing time than
+the actual database operations themselves.
+
+<P>
+On the other hand, for applications that have few writes in comparison
+to the number of read accesses, this aggressive caching can be a major
+win. Consider a Slashdot-like discussion forum that divides the load
+among several Web servers. If news items and postings are represented
+by objects and accessed through ZEO, then the most heavily accessed
+objects - the most recent or most popular postings - will very
+quickly wind up in the caches of the
+<tt class="class">ClientStorage</tt> instances on the front-end servers. The
+back-end ZEO server will do relatively little work, only being called
+upon to return the occasional older posting that's requested, and to
+send the occasional invalidate message when a new posting is added.
+The ZEO server isn't going to be contacted for every single request,
+so its workload will remain manageable.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A href="zeo.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A href="zeo.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node24.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<b class="navlabel">Up:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node24.html">3.2 Installing ZEO</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node24.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>3.2 Installing ZEO</title>
+<META NAME="description" CONTENT="3.2 Installing ZEO">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node27.html">
+<LINK REL="previous" HREF="node23.html">
+<LINK REL="up" href="zeo.html">
+<LINK REL="next" HREF="node25.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node23.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A href="zeo.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node25.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node23.html">3.1 How ZEO Works</A>
+<b class="navlabel">Up:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node25.html">3.2.1 Requirements</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000420000000000000000">
+3.2 Installing ZEO</A>
+</H2>
+
+<P>
+This section covers how to install the ZEO package, and how to
+configure and run a ZEO Storage Server on a machine.
+
+<P>
+
+<p><hr>
+<!--Table of Child-Links-->
+<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></a>
+
+<UL>
+<LI><A href="node25.html">3.2.1 Requirements</a>
+<LI><A href="node26.html">3.2.2 Installation</a>
+</ul>
+<!--End of Table of Child-Links-->
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node23.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A href="zeo.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node25.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node23.html">3.1 How ZEO Works</A>
+<b class="navlabel">Up:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node25.html">3.2.1 Requirements</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node25.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>3.2.1 Requirements</title>
+<META NAME="description" CONTENT="3.2.1 Requirements">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node26.html">
+<LINK REL="previous" HREF="node24.html">
+<LINK REL="up" HREF="node24.html">
+<LINK REL="next" HREF="node26.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node24.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node24.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node26.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node24.html">3.2 Installing ZEO</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node24.html">3.2 Installing ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node26.html">3.2.2 Installation</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H3><A NAME="SECTION000421000000000000000">
+3.2.1 Requirements</A>
+</H3>
+
+<P>
+To run a ZEO server, you'll need Python 1.5.2 or 2.0, and the ZODB
+packages from <a class="url" href="http://www.amk.ca/files/zodb/">http://www.amk.ca/files/zodb/</a>have to be installed.
+
+<P>
+<i>Note for Python 1.5.2 users</i>: ZEO requires updated versions
+of the <tt class="module">asyncore.py</tt> and <tt class="module">asynchat.py</tt> modules that are
+included in 1.5.2's standard library. Current versions of the ZODB
+distribution install private versions of these modules, so you
+shouldn't need to grab updated versions yourself. (The symptom of
+this problem is a traceback on attempting to run a ZEO client program:
+the traceback is ``TypeError: too many arguments; expected 2, got 3''
+around line 100 of <span class="file">smac.py</span>.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node24.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node24.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node26.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node24.html">3.2 Installing ZEO</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node24.html">3.2 Installing ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node26.html">3.2.2 Installation</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node26.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>3.2.2 Installation</title>
+<META NAME="description" CONTENT="3.2.2 Installation">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="previous" HREF="node25.html">
+<LINK REL="up" HREF="node24.html">
+<LINK REL="next" HREF="node27.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node25.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node24.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node27.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node25.html">3.2.1 Requirements</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node24.html">3.2 Installing ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node27.html">3.3 Configuring and Running</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H3><A NAME="SECTION000422000000000000000">
+3.2.2 Installation</A>
+</H3>
+
+<P>
+Installing the ZEO package is easy. Just run <code>python setup.py
+install</code>. This will install the ZEO/ package into your Python
+installation, and copy various files into their proper locations:
+<span class="file">zeo.conf</span> will be put into <span class="file">/usr/local/etc/</span>, a <span class="file">zeo</span> startup
+script will be put in <span class="file">/etc/rc.d/init.d/</span>, and the <span class="file">zeod</span>
+daemon program will be placed in <span class="file">/usr/local/bin</span>.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node25.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node24.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node27.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node25.html">3.2.1 Requirements</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node24.html">3.2 Installing ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node27.html">3.3 Configuring and Running</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node27.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>3.3 Configuring and Running a ZEO Server</title>
+<META NAME="description" CONTENT="3.3 Configuring and Running a ZEO Server">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node28.html">
+<LINK REL="previous" HREF="node24.html">
+<LINK REL="up" href="zeo.html">
+<LINK REL="next" HREF="node28.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node26.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A href="zeo.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node28.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node26.html">3.2.2 Installation</A>
+<b class="navlabel">Up:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node28.html">3.4 Testing the ZEO</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000430000000000000000">
+3.3 Configuring and Running a ZEO Server</A>
+</H2>
+
+<P>
+Edit <code>/usr/local/etc/zeo.conf</code> appropriately for your desired
+setup. This configuration file controls the port on which ZEO will
+listen for connections, the user and group IDs under which the server
+will be executed, and the location of the concrete <tt class="class">Storage</tt>
+object that will be made network-accessible.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node26.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A href="zeo.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node28.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node26.html">3.2.2 Installation</A>
+<b class="navlabel">Up:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node28.html">3.4 Testing the ZEO</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node28.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>3.4 Testing the ZEO Installation</title>
+<META NAME="description" CONTENT="3.4 Testing the ZEO Installation">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node29.html">
+<LINK REL="previous" HREF="node27.html">
+<LINK REL="up" href="zeo.html">
+<LINK REL="next" HREF="node29.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node27.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A href="zeo.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node29.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node27.html">3.3 Configuring and Running</A>
+<b class="navlabel">Up:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node29.html">3.5 ZEO Programming Notes</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000440000000000000000">
+3.4 Testing the ZEO Installation</A>
+</H2>
+
+<P>
+Once a ZEO server is up and running, using it is just like using ZODB
+with a more conventional disk-based storage; no new programming
+details are introduced by using a remote server. The only difference
+is that programs must create a <tt class="class">ClientStorage</tt> instance instead
+of a <tt class="class">FileStorage</tt> instance. From that point onward, ZODB-based
+code is happily unaware that objects are being retrieved from a ZEO
+server, and not from the local disk.
+
+<P>
+As an example, and to test whether ZEO is working correctly, try
+running the following lines of code, which will connect to the server,
+add some bits of data to the root of the ZODB, and commits the
+transaction:
+
+<P>
+<dl><dd><pre class="verbatim">
+from ZEO import ClientStorage
+from ZODB import DB
+
+# Change next line to connect to your ZEO server
+addr = ('kronos.example.com', 1975)
+storage = ClientStorage.ClientStorage(addr)
+db = DB(storage)
+conn = db.open()
+root = conn.root()
+
+# Store some things in the root
+root['list'] = ['a', 'b', 1.0, 3]
+root['dict'] = {'a':1, 'b':4}
+
+# Commit the transaction
+get_transaction().commit()
+</pre></dl>
+
+<P>
+If this code runs properly, then your ZEO server is working correctly.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node27.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A href="zeo.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node29.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node27.html">3.3 Configuring and Running</A>
+<b class="navlabel">Up:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node29.html">3.5 ZEO Programming Notes</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node29.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>3.5 ZEO Programming Notes</title>
+<META NAME="description" CONTENT="3.5 ZEO Programming Notes">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node30.html">
+<LINK REL="previous" HREF="node28.html">
+<LINK REL="up" href="zeo.html">
+<LINK REL="next" HREF="node30.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node28.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A href="zeo.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node30.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node28.html">3.4 Testing the ZEO</A>
+<b class="navlabel">Up:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node30.html">3.6 Sample Application: chatter.py</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000450000000000000000">
+3.5 ZEO Programming Notes</A>
+</H2>
+
+<P>
+XXX The Connection.sync() method and its necessity (if it works at all!)
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node28.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A href="zeo.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node30.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node28.html">3.4 Testing the ZEO</A>
+<b class="navlabel">Up:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node30.html">3.6 Sample Application: chatter.py</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node3.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>1.1 What is the ZODB?</title>
+<META NAME="description" CONTENT="1.1 What is the ZODB?">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node4.html">
+<LINK REL="previous" HREF="node2.html">
+<LINK REL="up" HREF="node2.html">
+<LINK REL="next" HREF="node4.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node2.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node2.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
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+<td><A HREF="node4.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node2.html">1 Introduction</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node2.html">1 Introduction</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node4.html">1.2 OODBs vs. Relational</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000210000000000000000">
+1.1 What is the ZODB?</A>
+</H2>
+
+<P>
+The ZODB is a persistence system for Python objects. Persistent
+programming languages provide facilities that automatically write
+objects to disk and read them in again when they're required by a
+running program. By installing the ZODB, you add such facilities to
+Python.
+
+<P>
+It's certainly possible to build your own system for making Python
+objects persistent. The usual starting points are the <tt class="module">pickle</tt>
+module, for converting objects into a string representation, and
+various database modules, such as the <tt class="module">gdbm</tt> or <tt class="module">bsddb</tt>
+modules, that provide ways to write strings to disk and read them
+back. It's straightforward to combine the <tt class="module">pickle</tt> module and
+a database module to store and retrieve objects, and in fact the
+<tt class="module">shelve</tt> module, included in Python's standard library, does
+this.
+
+<P>
+The downside is that the programmer has to explicitly manage objects,
+reading an object when it's needed and writing it out to disk when the
+object is no longer required. The ZODB manages objects for you,
+keeping them in a cache and writing them out if they haven't been
+accessed in a while.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node2.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node2.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node4.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node2.html">1 Introduction</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node2.html">1 Introduction</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node4.html">1.2 OODBs vs. Relational</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node30.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>3.6 Sample Application: chatter.py</title>
+<META NAME="description" CONTENT="3.6 Sample Application: chatter.py">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="previous" HREF="node29.html">
+<LINK REL="up" href="zeo.html">
+<LINK REL="next" HREF="node31.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node29.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A href="zeo.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node31.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node29.html">3.5 ZEO Programming Notes</A>
+<b class="navlabel">Up:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node31.html">4 Transactions and Versioning</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000460000000000000000">
+3.6 Sample Application: chatter.py</A>
+</H2>
+
+<P>
+For an example application, we'll build a little chat application.
+What's interesting is that none of the application's code deals with
+network programming at all; instead, an object will hold chat
+messages, and be magically shared between all the clients through ZEO.
+I won't present the complete script here; it's included in my ZODB
+distribution, and you can download it from
+<a class="url" href="http://www.amk.ca/zodb/demos/">http://www.amk.ca/zodb/demos/</a>. Only the interesting portions of
+the code will be covered here.
+
+<P>
+The basic data structure is the <tt class="class">ChatSession</tt> object,
+which provides an <tt class="method">add_message()</tt> method that adds a
+message, and a <tt class="method">new_messages()</tt> method that returns a list
+of new messages that have accumulated since the last call to
+<tt class="method">new_messages()</tt>. Internally, <tt class="class">ChatSession</tt>
+maintains a B-tree that uses the time as the key, and stores the
+message as the corresponding value.
+
+<P>
+The constructor for <tt class="class">ChatSession</tt> is pretty simple; it simply
+creates an attribute containing a B-tree:
+
+<P>
+<dl><dd><pre class="verbatim">
+class ChatSession(Persistent):
+ def __init__(self, name):
+ self.name = name
+ # Internal attribute: _messages holds all the chat messages.
+ self._messages = BTree.BTree()
+</pre></dl>
+
+<P>
+<tt class="method">add_message()</tt> has to add a message to the
+<code>_messages</code> B-tree. A complication is that it's possible
+that some other client is trying to add a message at the same time;
+when this happens, the client that commits first wins, and the second
+client will get a <tt class="exception">ConflictError</tt> exception when it tries to
+commit. For this application, <tt class="exception">ConflictError</tt> isn't serious
+but simply means that the operation has to be retried; other
+applications might treat it as a fatal error. The code uses
+<code>try...except...else</code> inside a <code>while</code> loop,
+breaking out of the loop when the commit works without raising an
+exception.
+
+<P>
+<dl><dd><pre class="verbatim">
+ def add_message(self, message):
+ """Add a message to the channel.
+ message -- text of the message to be added
+ """
+
+ while 1:
+ try:
+ now = time.time()
+ self._messages[now] = message
+ get_transaction().commit()
+ except ConflictError:
+ # Conflict occurred; this process should pause and
+ # wait for a little bit, then try again.
+ time.sleep(.2)
+ pass
+ else:
+ # No ConflictError exception raised, so break
+ # out of the enclosing while loop.
+ break
+ # end while
+</pre></dl>
+
+<P>
+<tt class="method">new_messages()</tt> introduces the use of <i>volatile</i>
+attributes. Attributes of a persistent object that begin with
+<code>_v_</code> are considered volatile and are never stored in the
+database. <tt class="method">new_messages()</tt> needs to store the last time
+the method was called, but if the time was stored as a regular
+attribute, its value would be committed to the database and shared
+with all the other clients. <tt class="method">new_messages()</tt> would then
+return the new messages accumulated since any other client called
+<tt class="method">new_messages()</tt>, which isn't what we want.
+
+<P>
+<dl><dd><pre class="verbatim">
+ def new_messages(self):
+ "Return new messages."
+
+ # self._v_last_time is the time of the most recent message
+ # returned to the user of this class.
+ if not hasattr(self, '_v_last_time'):
+ self._v_last_time = 0
+
+ new = []
+ T = self._v_last_time
+
+ for T2, message in self._messages.items():
+ if T2 > T:
+ new.append(message)
+ self._v_last_time = T2
+
+ return new
+</pre></dl>
+
+<P>
+This application is interesting because it uses ZEO to easily share a
+data structure; ZEO and ZODB are being used for their networking
+ability, not primarily for their data storage ability. I can foresee
+many interesting applications using ZEO in this way:
+
+<P>
+
+<UL>
+<LI>With a Tkinter front-end, and a cleverer, more scalable data
+ structure, you could build a shared whiteboard using the same
+ technique.
+
+<P>
+</LI>
+<LI>A shared chessboard object would make writing a networked chess
+ game easy.
+
+<P>
+</LI>
+<LI>You could create a Python class containing a CD's title and
+ track information. To make a CD database, a read-only ZEO server
+ could be opened to the world, or an HTTP or XML-RPC interface could
+ be written on top of the ZODB.
+
+<P>
+</LI>
+<LI>A program like Quicken could use a ZODB on the local disk to
+ store its data. This avoids the need to write and maintain
+ specialized I/O code that reads in your objects and writes them out;
+ instead you can concentrate on the problem domain, writing objects
+ that represent cheques, stock portfolios, or whatever.
+
+<P>
+</LI>
+</UL>
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node29.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A href="zeo.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node31.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node29.html">3.5 ZEO Programming Notes</A>
+<b class="navlabel">Up:</b> <a class="sectref" href="zeo.html">3 ZEO</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node31.html">4 Transactions and Versioning</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node31.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>4 Transactions and Versioning</title>
+<META NAME="description" CONTENT="4 Transactions and Versioning">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node36.html">
+<LINK REL="previous" href="zeo.html">
+<LINK REL="up" HREF="zodb.html">
+<LINK REL="next" HREF="node32.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node30.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node32.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node30.html">3.6 Sample Application: chatter.py</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node32.html">4.1 Subtransactions</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H1><A NAME="SECTION000500000000000000000">
+4 Transactions and Versioning</A>
+</H1>
+
+<P>
+
+<p><hr>
+<!--Table of Child-Links-->
+<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></a>
+
+<UL>
+<LI><A href="node32.html">4.1 Subtransactions</a>
+<LI><A href="node33.html">4.2 Undoing Changes</a>
+<LI><A href="node34.html">4.3 Versions</a>
+<LI><A href="node35.html">4.4 Multithreaded ZODB Programs</a>
+</ul>
+<!--End of Table of Child-Links-->
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node30.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node32.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node30.html">3.6 Sample Application: chatter.py</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node32.html">4.1 Subtransactions</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node32.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>4.1 Subtransactions</title>
+<META NAME="description" CONTENT="4.1 Subtransactions">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node33.html">
+<LINK REL="previous" HREF="node31.html">
+<LINK REL="up" HREF="node31.html">
+<LINK REL="next" HREF="node33.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node31.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node31.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node33.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node31.html">4 Transactions and Versioning</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node31.html">4 Transactions and Versioning</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node33.html">4.2 Undoing Changes</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000510000000000000000">
+4.1 Subtransactions</A>
+</H2>
+
+<P>
+Subtransactions can be created within a transaction. Each
+subtransaction can be individually committed and aborted, but the
+changes within a subtransaction are not truly committed until the
+containing transaction is committed.
+
+<P>
+The primary purpose of subtransactions is to decrease the memory usage
+of transactions that touch a very large number of objects. Consider a
+transaction during which 200,000 objects are modified. All the
+objects that are modified in a single transaction have to remain in
+memory until the transaction is committed, because the ZODB can't
+discard them from the object cache. This can potentially make the
+memory usage quite large. With subtransactions, a commit can be be
+performed at intervals, say, every 10,000 objects. Those 10,000
+objects are then written to permanent storage and can be purged from
+the cache to free more space.
+
+<P>
+To commit a subtransaction instead of a full transaction,
+pass a true value to the <tt class="method">commit()</tt>
+or <tt class="method">abort()</tt> method of the <tt class="class">Transaction</tt> object.
+
+<P>
+<dl><dd><pre class="verbatim">
+# Commit a subtransaction
+get_transaction().commit(1)
+
+# Abort a subtransaction
+get_transaction().abort(1)
+</pre></dl>
+
+<P>
+A new subtransaction is automatically started on committing or
+aborting the previous subtransaction.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node31.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node31.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node33.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node31.html">4 Transactions and Versioning</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node31.html">4 Transactions and Versioning</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node33.html">4.2 Undoing Changes</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node33.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>4.2 Undoing Changes</title>
+<META NAME="description" CONTENT="4.2 Undoing Changes">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node34.html">
+<LINK REL="previous" HREF="node32.html">
+<LINK REL="up" HREF="node31.html">
+<LINK REL="next" HREF="node34.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node32.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node31.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
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+<td><A HREF="node34.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node32.html">4.1 Subtransactions</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node31.html">4 Transactions and Versioning</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node34.html">4.3 Versions</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000520000000000000000">
+4.2 Undoing Changes</A>
+</H2>
+
+<P>
+Some types of <tt class="class">Storage</tt> support undoing a transaction even after
+it's been committed. You can tell if this is the case by calling the
+<tt class="method">supportsUndo()</tt> method of the <tt class="class">DB</tt> instance, which
+returns true if the underlying storage supports undo. Alternatively
+you can call the <tt class="method">supportsUndo()</tt> method on the underlying
+storage instance.
+
+<P>
+If a database supports undo, then the <tt class="method">undoLog(<var>start</var>,
+<var>end</var><big>[</big>, func<big>]</big>)</tt> method on the <tt class="class">DB</tt> instance returns
+the log of past transactions, returning transactions between the times
+<var>start</var> and <var>end</var>, measured in seconds from the epoch.
+If present, <var>func</var> is a function that acts as a filter on the
+transactions to be returned; it's passed a dictionary representing
+each transaction, and only transactions for which <var>func</var> returns
+true will be included in the list of transactions returned to the
+caller of <tt class="method">undoLog()</tt>. The dictionary contains keys for
+various properties of the transaction. The most important keys are
+"<tt class="samp">id</tt>", for the transaction ID, and "<tt class="samp">time</tt>", for the time at
+which the transaction was committed.
+
+<P>
+<dl><dd><pre class="verbatim">
+>>> print storage.undoLog(0, sys.maxint)
+[{'description': '',
+ 'id': 'AzpGEGqU/0QAAAAAAAAGMA',
+ 'time': 981126744.98,
+ 'user_name': ''},
+ {'description': '',
+ 'id': 'AzpGC/hUOKoAAAAAAAAFDQ',
+ 'time': 981126478.202,
+ 'user_name': ''}
+ ...
+</pre></dl>
+
+<P>
+To store a description and a user name on a commit, get the current
+transaction and call the <tt class="method">note(<var>text</var>)</tt> method to store a
+description, and the
+<tt class="method">setUser(<var>user_name</var>)</tt> method to store the user name.
+While <tt class="method">setUser()</tt> overwrites the current user name and replaces
+it with the new value, the <tt class="method">note()</tt> method always adds the text
+to the transaction's description, so it can be called several times to
+log several different changes made in the course of a single
+transaction.
+
+<P>
+<dl><dd><pre class="verbatim">
+get_transaction().setUser('amk')
+get_transaction().note('Change ownership')
+</pre></dl>
+
+<P>
+To undo a transaction, call the <tt class="method">DB.undo(<var>id</var>)</tt> method,
+passing it the ID of the transaction to undo. If the transaction
+can't be undone, a <tt class="exception">ZODB.POSException.UndoError</tt> exception
+will be raised, with the message ``non-undoable
+transaction''. Usually this will happen because later transactions
+modified the objects affected by the transaction you're trying to
+undo.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node32.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node31.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node34.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node32.html">4.1 Subtransactions</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node31.html">4 Transactions and Versioning</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node34.html">4.3 Versions</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node34.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>4.3 Versions</title>
+<META NAME="description" CONTENT="4.3 Versions">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node35.html">
+<LINK REL="previous" HREF="node33.html">
+<LINK REL="up" HREF="node31.html">
+<LINK REL="next" HREF="node35.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node33.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node31.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node35.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node33.html">4.2 Undoing Changes</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node31.html">4 Transactions and Versioning</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node35.html">4.4 Multithreaded ZODB Programs</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000530000000000000000">
+4.3 Versions</A>
+</H2>
+
+<P>
+While many subtransactions can be contained within a single regular
+transaction, it's also possible to contain many regular transactions
+within a long-running transaction, called a version in ZODB
+terminology. Inside a version, any number of transactions can be
+created and committed or rolled back, but the changes within a version
+are not made visible to other connections to the same ZODB.
+
+<P>
+Not all storages support versions, but you can test for versioning
+ability by calling <tt class="method">supportsVersions()</tt> method of the
+<tt class="class">DB</tt> instance, which returns true if the underlying storage
+supports versioning.
+
+<P>
+A version can be selected when creating the <tt class="class">Connection</tt>
+instance using the <tt class="method">DB.open(<big>[</big><var>version</var><big>]</big>)</tt> method.
+The <var>version</var> argument must be a string that will be used as the
+name of the version.
+
+<P>
+<dl><dd><pre class="verbatim">
+vers_conn = db.open(version='Working version')
+</pre></dl>
+
+<P>
+Transactions can then be committed and aborted using this versioned
+connection. Other connections that don't specify a version, or
+provide a different version name, will not see changes committed
+within the version named "<tt class="samp">Working version</tt>". To commit or abort a
+version, which will either make the changes visible to all clients or
+roll them back, call the <tt class="method">DB.commitVersion()</tt> or
+<tt class="method">DB.abortVersion()</tt> methods.
+XXX what are the source and dest arguments for?
+
+<P>
+The ZODB makes no attempt to reconcile changes between different
+versions. Instead, the first version which modifies an object will
+gain a lock on that object. Attempting to modify the object from a
+different version or from an unversioned connection will cause a
+<tt class="exception">ZODB.POSException.VersionLockError</tt> to be raised:
+
+<P>
+<dl><dd><pre class="verbatim">
+from ZODB.POSException import VersionLockError
+
+try:
+ get_transaction().commit()
+except VersionLockError, (obj_id, version):
+ print ('Cannot commit; object %s '
+ 'locked by version %s' % (obj_id, version))
+</pre></dl>
+
+<P>
+The exception provides the ID of the locked object, and the name of
+the version having a lock on it.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node33.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node31.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node35.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node33.html">4.2 Undoing Changes</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node31.html">4 Transactions and Versioning</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node35.html">4.4 Multithreaded ZODB Programs</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node35.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>4.4 Multithreaded ZODB Programs</title>
+<META NAME="description" CONTENT="4.4 Multithreaded ZODB Programs">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="previous" HREF="node34.html">
+<LINK REL="up" HREF="node31.html">
+<LINK REL="next" HREF="node36.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node34.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node31.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node36.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node34.html">4.3 Versions</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node31.html">4 Transactions and Versioning</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node36.html">5 Related Modules</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000540000000000000000">
+4.4 Multithreaded ZODB Programs</A>
+</H2>
+
+<P>
+ZODB databases can be accessed from multithreaded Python programs.
+The <tt class="class">Storage</tt> and <tt class="class">DB</tt> instances can be shared among
+several threads, as long as individual <tt class="class">Connection</tt> instances
+are created for each thread.
+
+<P>
+XXX I can't think of anything else to say about multithreaded ZODB
+programs. Suggestions? An example program?
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node34.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node31.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
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+<td><A HREF="node36.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node34.html">4.3 Versions</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node31.html">4 Transactions and Versioning</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node36.html">5 Related Modules</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node36.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>5 Related Modules</title>
+<META NAME="description" CONTENT="5 Related Modules">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node40.html">
+<LINK REL="previous" HREF="node31.html">
+<LINK REL="up" HREF="zodb.html">
+<LINK REL="next" HREF="node37.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node35.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node37.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node35.html">4.4 Multithreaded ZODB Programs</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node37.html">5.1 ZODB.PersistentMapping</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H1><A NAME="SECTION000600000000000000000">
+5 Related Modules</A>
+</H1>
+
+<P>
+The ZODB package includes a number of related modules that provide
+useful data types such as BTrees or full-text indexes.
+
+<P>
+
+<p><hr>
+<!--Table of Child-Links-->
+<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></a>
+
+<UL>
+<LI><A href="node37.html">5.1 <tt class="module">ZODB.PersistentMapping</tt></a>
+<LI><A href="node38.html">5.2 <tt class="module">ZODB.PersistentList</tt></a>
+<LI><A href="node39.html">5.3 B-tree Modules</a>
+</ul>
+<!--End of Table of Child-Links-->
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node35.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node37.html"><img src="/python/writing/icons/next.gif"
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+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node35.html">4.4 Multithreaded ZODB Programs</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node37.html">5.1 ZODB.PersistentMapping</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node37.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>5.1 ZODB.PersistentMapping</title>
+<META NAME="description" CONTENT="5.1 ZODB.PersistentMapping">
+<META NAME="keywords" CONTENT="zodb">
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+<meta http-equiv="Content-Type" content="text/html; charset=">
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+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node36.html">5 Related Modules</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node36.html">5 Related Modules</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node38.html">5.2 ZODB.PersistentList</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000610000000000000000">
+5.1 <tt class="module">ZODB.PersistentMapping</tt></A>
+</H2>
+
+<P>
+The <tt class="class">PersistentMapping</tt> class is a wrapper for mapping objects
+that will set the dirty bit when the mapping is modified by setting or
+deleting a key.
+
+<P>
+<dl><dt><b><a name="l2h-1"><tt class="function">PersistentMapping</tt></a></b>(<var>container = {}</var>)
+<dd>
+Create a <tt class="class">PersistentMapping</tt> object that wraps the
+mapping object <var>container</var>. If you don't specify a
+value for <var>container</var>, a regular Python dictionary is used.
+</dl>
+
+<P>
+<tt class="class">PersistentMapping</tt> objects support all the same methods as
+Python dictionaries do.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node36.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
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+<td><A HREF="node36.html"><img src="/python/writing/icons/up.gif"
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+<td><A HREF="node38.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node36.html">5 Related Modules</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node36.html">5 Related Modules</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node38.html">5.2 ZODB.PersistentList</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node38.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>5.2 ZODB.PersistentList</title>
+<META NAME="description" CONTENT="5.2 ZODB.PersistentList">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node39.html">
+<LINK REL="previous" HREF="node37.html">
+<LINK REL="up" HREF="node36.html">
+<LINK REL="next" HREF="node39.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node37.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node36.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node39.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node37.html">5.1 ZODB.PersistentMapping</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node36.html">5 Related Modules</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node39.html">5.3 B-tree Modules</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000620000000000000000">
+5.2 <tt class="module">ZODB.PersistentList</tt></A>
+</H2>
+
+<P>
+The <tt class="class">PersistentList</tt> class is a wrapper for mutable sequence objects,
+much as <tt class="class">PersistentMapping</tt> is a wrapper for mappings.
+
+<P>
+<dl><dt><b><a name="l2h-2"><tt class="function">PersistentList</tt></a></b>(<var>initlist = []</var>)
+<dd>
+Create a <tt class="class">PersistentList</tt> object that wraps the
+mutable sequence object <var>initlist</var>. If you don't specify a
+value for <var>initlist</var>, a regular Python list is used.
+</dl>
+
+<P>
+<tt class="class">PersistentList</tt> objects support all the same methods as
+Python lists do.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node37.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node36.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
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+<td><A HREF="node39.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node37.html">5.1 ZODB.PersistentMapping</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node36.html">5 Related Modules</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node39.html">5.3 B-tree Modules</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node39.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>5.3 B-tree Modules</title>
+<META NAME="description" CONTENT="5.3 B-tree Modules">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="previous" HREF="node38.html">
+<LINK REL="up" HREF="node36.html">
+<LINK REL="next" HREF="node40.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node38.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
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+<td><A HREF="node36.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
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+<td><A HREF="node40.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node38.html">5.2 ZODB.PersistentList</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node36.html">5 Related Modules</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node40.html">A. Resources</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000630000000000000000">
+5.3 B-tree Modules</A>
+</H2>
+
+<P>
+When programming with the ZODB, Python dictionaries aren't always what
+you need. The most important case is where you want to store a very
+large mapping. When a Python dictionary is accessed in a ZODB, the
+whole dictionary has to be unpickled and brought into memory. If
+you're storing something very large, such as a 100,000-entry user
+database, unpickling such a large object will be slow. B-trees are a
+balanced tree data structure that behave like a mapping but distribute
+keys throughout a number of tree nodes. Nodes are then only unpickled
+and brought into memory as they're accessed, so the entire tree
+doesn't have to occupy memory (unless you really are touching every
+single key).
+
+<P>
+There are four different BTree modules provided. One of them, the
+<tt class="module">BTree</tt> module, provides the most general data type; the keys
+and values in the B-tree can be any Python object. Some specialized B-tree
+modules require that the keys, and perhaps even the values, to be of a
+certain type, and provide faster performance because of this limitation.
+
+<P>
+<DL COMPACT>
+<DT> <tt class="module">IOBTree</tt> </DT>
+<DD>requires the keys to be integers.
+The module name reminds you of this; the <tt class="module">IOBTree</tt> module
+maps Integers to Objects.
+
+<P>
+</DD>
+<DT> <tt class="module">OIBTree</tt> </DT>
+<DD>requires the values to be integers,
+mapping Objects to Integers.
+
+<P>
+</DD>
+<DT> <tt class="module">IIBTree</tt> </DT>
+<DD>is strictest, requiring that both keys and values must be integers.
+
+<P>
+</DD>
+</DL>
+
+<P>
+To use a B-tree, simply import the desired module and call the
+constructor, always named <tt class="function">BTree()</tt>, to get a B-tree
+instance, and then use it like any other mapping:
+
+<P>
+<dl><dd><pre class="verbatim">
+import IIBTree
+iimap = IIBTree.BTree()
+iimap[1972] = 27
+</pre></dl>
+
+<P>
+
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node38.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
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+<td><A HREF="node36.html"><img src="/python/writing/icons/up.gif"
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+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node38.html">5.2 ZODB.PersistentList</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node36.html">5 Related Modules</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node40.html">A. Resources</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node4.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>1.2 OODBs vs. Relational DBs</title>
+<META NAME="description" CONTENT="1.2 OODBs vs. Relational DBs">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node5.html">
+<LINK REL="previous" HREF="node3.html">
+<LINK REL="up" HREF="node2.html">
+<LINK REL="next" HREF="node5.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node3.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
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+<td><A HREF="node2.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
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+<td><A HREF="node5.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
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+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node3.html">1.1 What is the</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node2.html">1 Introduction</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node5.html">1.3 What is ZEO?</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000220000000000000000">
+1.2 OODBs vs. Relational DBs</A>
+</H2>
+
+<P>
+Another way to look at it is that the ZODB is a Python-specific
+object-oriented database (OODB). Commercial object databases for C++
+or Java often require that you jump through some hoops, such as using
+a special preprocessor or avoiding certain data types. As we'll see,
+the ZODB has some hoops of its own to jump through, but in comparison
+the naturalness of the ZODB is astonishing.
+
+<P>
+Relational databases (RDBs) are far more common than OODBs.
+Relational databases store information in tables; a table consists of
+any number of rows, each row containing several columns of
+information. (Rows are more formally called relations, which is where
+the term ``relational database'' originates.)
+
+<P>
+Let's look at a concrete example. The example comes from my day job
+working for the MEMS Exchange, in a greatly simplified version. The
+job is to track process runs, which are lists of manufacturing steps
+to be performed in a semiconductor fab. A run is owned by a
+particular user, and has a name and assigned ID number. Runs consist
+of a number of operations; an operation is a single step to be
+performed, such as depositing something on a wafer or etching
+something off it.
+
+<P>
+Operations may have parameters, which are additional information
+required to perform an operation. For example, if you're depositing
+something on a wafer, you need to know two things: 1) what you're
+depositing, and 2) how much should be deposited. You might deposit
+100 microns of silicon oxide, or 1 micron of copper.
+
+<P>
+Mapping these structures to a relational database is straightforward:
+
+<P>
+<dl><dd><pre class="verbatim">
+CREATE TABLE runs (
+ int run_id,
+ varchar owner,
+ varchar title,
+ int acct_num,
+ primary key(run_id)
+);
+
+CREATE TABLE operations (
+ int run_id,
+ int step_num,
+ varchar process_id,
+ PRIMARY KEY(run_id, step_num),
+ FOREIGN KEY(run_id) REFERENCES runs(run_id),
+);
+
+CREATE TABLE parameters (
+ int run_id,
+ int step_num,
+ varchar param_name,
+ varchar param_value,
+ PRIMARY KEY(run_id, step_num, param_name)
+ FOREIGN KEY(run_id, step_num)
+ REFERENCES operations(run_id, step_num),
+);
+</pre></dl>
+
+<P>
+In Python, you would write three classes named <tt class="class">Run</tt>,
+<tt class="class">Operation</tt>, and <tt class="class">Parameter</tt>. I won't present code for
+defining these classes, since that code is uninteresting at this
+point. Each class would contain a single method to begin with, an
+<tt class="method">__init__</tt> method that assigns default values, such as 0 or
+<code>None</code>, to each attribute of the class.
+
+<P>
+It's not difficult to write Python code that will create a <tt class="class">Run</tt>
+instance and populate it with the data from the relational tables;
+with a little more effort, you can build a straightforward tool,
+usually called an object-relational mapper, to do this automatically.
+(See
+<a class="url" href="http://www.amk.ca/python/unmaintained/ordb.html">http://www.amk.ca/python/unmaintained/ordb.html</a> for a quick hack
+at a Python object-relational mapper, and
+<a class="url" href="http://www.python.org/workshops/1997-10/proceedings/shprentz.html">http://www.python.org/workshops/1997-10/proceedings/shprentz.html</a>for Joel Shprentz's more successful implementation of the same idea;
+Unlike mine, Shprentz's system has been used for actual work.)
+
+<P>
+However, it is difficult to make an object-relational mapper
+reasonably quick; a simple-minded implementation like mine is quite
+slow because it has to do several queries to access all of an object's
+data. Higher performance object-relational mappers cache objects to
+improve performance, only performing SQL queries when they actually
+need to.
+
+<P>
+That helps if you want to access run number 123 all of a sudden. But
+what if you want to find all runs where a step has a parameter named
+'thickness' with a value of 2.0? In the relational version, you have
+two unappealing choices:
+
+<P>
+
+<OL>
+<LI>Write a specialized SQL query for this case: <code>SELECT run_id
+ FROM operations WHERE param_name = 'thickness' AND param_value = 2.0</code>
+
+<P>
+If such queries are common, you can end up with lots of specialized
+ queries. When the database tables get rearranged, all these queries
+ will need to be modified.
+
+<P>
+</LI>
+<LI>An object-relational mapper doesn't help much. Scanning
+ through the runs means that the the mapper will perform the required
+ SQL queries to read run #1, and then a simple Python loop can check
+ whether any of its steps have the parameter you're looking for.
+ Repeat for run #2, 3, and so forth. This does a vast
+ number of SQL queries, and therefore is incredibly slow.
+
+<P>
+</LI>
+</OL>
+
+<P>
+An object database such as ZODB simply stores internal pointers from
+object to object, so reading in a single object is much faster than
+doing a bunch of SQL queries and assembling the results. Scanning all
+runs, therefore, is still inefficient, but not grossly inefficient.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node3.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
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+<td><img src="/python/writing/icons/blank.gif"
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+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
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+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node3.html">1.1 What is the</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node2.html">1 Introduction</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node5.html">1.3 What is ZEO?</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node40.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>A. Resources</title>
+<META NAME="description" CONTENT="A. Resources">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node41.html">
+<LINK REL="previous" HREF="node36.html">
+<LINK REL="up" HREF="zodb.html">
+<LINK REL="next" HREF="node41.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node39.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node39.html">5.3 B-tree Modules</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H1><A NAME="SECTION000700000000000000000">
+A. Resources</A>
+</H1>
+
+<P>
+ZODB HOWTO, by Michel Pelletier:
+
+<BR>
+Goes into slightly more detail about the rules for writing applications using the ZODB.
+
+<BR><a class="url" href="http://www.zope.org/Members/michel/HowTos/ZODB-How-To">http://www.zope.org/Members/michel/HowTos/ZODB-How-To</a>
+<P>
+Introduction to the Zope Object Database, by Jim Fulton:
+
+<BR>
+Goes into much greater detail, explaining advanced uses of the ZODB and
+how it's actually implemented. A definitive reference, and highly recommended.
+
+<BR><a class="url" href="http://www.python.org/workshops/2000-01/proceedings/papers/fulton/zodb3.html">http://www.python.org/workshops/2000-01/proceedings/papers/fulton/zodb3.html</a>
+<P>
+Download link for ZEO:
+<BR><a class="url" href="http://www.zope.org/Products/ZEO/">http://www.zope.org/Products/ZEO/</a>
+<P>
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node39.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node39.html">5.3 B-tree Modules</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node41.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>B. GNU Free Documentation License</title>
+<META NAME="description" CONTENT="B. GNU Free Documentation License">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" href="about.html">
+<LINK REL="previous" HREF="node40.html">
+<LINK REL="up" HREF="zodb.html">
+<LINK REL="next" HREF="node42.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node40.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node42.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node40.html">A. Resources</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node42.html">Preamble</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H1><A NAME="SECTION000800000000000000000">
+B. GNU Free Documentation License</A>
+</H1>
+
+<P>
+Version 1.1, March 2000
+<BR>
+<P>
+Copyright <SPAN CLASS="MATH"><IMG
+ WIDTH="20" HEIGHT="29" ALIGN="MIDDLE" BORDER="0"
+ SRC="img1.gif"
+ ALT="$\copyright$"></SPAN> 2000 Free Software Foundation, Inc.
+<BR>
+59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+<BR>
+Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+<P>
+
+<p><hr>
+<!--Table of Child-Links-->
+<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></a>
+
+<UL>
+<LI><A href="node42.html">Preamble</a>
+<LI><A href="node43.html">B..1 Applicability and Definitions</a>
+<LI><A href="node44.html">B..2 Verbatim Copying</a>
+<LI><A href="node45.html">B..3 Copying in Quantity</a>
+<LI><A href="node46.html">B..4 Modifications</a>
+<LI><A href="node47.html">B..5 Combining Documents</a>
+<LI><A href="node48.html">B..6 Collections of Documents</a>
+<LI><A href="node49.html">B..7 Aggregation With Independent Works</a>
+<LI><A href="node50.html">B..8 Translation</a>
+<LI><A href="node51.html">B..9 Termination</a>
+<LI><A href="node52.html">B..10 Future Revisions of This Licence</a>
+<LI><A href="node53.html">ADDENDUM: How to use this License for your documents</a>
+</ul>
+<!--End of Table of Child-Links-->
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node40.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node42.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node40.html">A. Resources</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node42.html">Preamble</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node42.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>Preamble</title>
+<META NAME="description" CONTENT="Preamble">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node43.html">
+<LINK REL="previous" HREF="node41.html">
+<LINK REL="up" HREF="node41.html">
+<LINK REL="next" HREF="node43.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node41.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node43.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node43.html">B..1 Applicability and Definitions</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000810000000000000000">
+Preamble</A>
+</H2>
+
+<P>
+The purpose of this License is to make a manual, textbook, or other
+written document ``free'' in the sense of freedom: to assure everyone
+the effective freedom to copy and redistribute it, with or without
+modifying it, either commercially or noncommercially. Secondarily,
+this License preserves for the author and publisher a way to get
+credit for their work, while not being considered responsible for
+modifications made by others.
+
+<P>
+This License is a kind of ``copyleft'', which means that derivative
+works of the document must themselves be free in the same sense. It
+complements the GNU General Public License, which is a copyleft
+license designed for free software.
+
+<P>
+We have designed this License in order to use it for manuals for free
+software, because free software needs free documentation: a free
+program should come with manuals providing the same freedoms that the
+software does. But this License is not limited to software manuals;
+it can be used for any textual work, regardless of subject matter or
+whether it is published as a printed book. We recommend this License
+principally for works whose purpose is instruction or reference.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node41.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node43.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node43.html">B..1 Applicability and Definitions</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node43.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>B..1 Applicability and Definitions</title>
+<META NAME="description" CONTENT="B..1 Applicability and Definitions">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node44.html">
+<LINK REL="previous" HREF="node42.html">
+<LINK REL="up" HREF="node41.html">
+<LINK REL="next" HREF="node44.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node42.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node44.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node42.html">Preamble</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node44.html">B..2 Verbatim Copying</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000820000000000000000">
+B..1 Applicability and Definitions</A>
+</H2>
+
+<P>
+This License applies to any manual or other work that contains a
+notice placed by the copyright holder saying it can be distributed
+under the terms of this License. The ``Document'', below, refers to any
+such manual or work. Any member of the public is a licensee, and is
+addressed as ``you''.
+
+<P>
+A ``Modified Version'' of the Document means any work containing the
+Document or a portion of it, either copied verbatim, or with
+modifications and/or translated into another language.
+
+<P>
+A ``Secondary Section'' is a named appendix or a front-matter section of
+the Document that deals exclusively with the relationship of the
+publishers or authors of the Document to the Document's overall subject
+(or to related matters) and contains nothing that could fall directly
+within that overall subject. (For example, if the Document is in part a
+textbook of mathematics, a Secondary Section may not explain any
+mathematics.) The relationship could be a matter of historical
+connection with the subject or with related matters, or of legal,
+commercial, philosophical, ethical or political position regarding
+them.
+
+<P>
+The ``Invariant Sections'' are certain Secondary Sections whose titles
+are designated, as being those of Invariant Sections, in the notice
+that says that the Document is released under this License.
+
+<P>
+The ``Cover Texts'' are certain short passages of text that are listed,
+as Front-Cover Texts or Back-Cover Texts, in the notice that says that
+the Document is released under this License.
+
+<P>
+A ``Transparent'' copy of the Document means a machine-readable copy,
+represented in a format whose specification is available to the
+general public, whose contents can be viewed and edited directly and
+straightforwardly with generic text editors or (for images composed of
+pixels) generic paint programs or (for drawings) some widely available
+drawing editor, and that is suitable for input to text formatters or
+for automatic translation to a variety of formats suitable for input
+to text formatters. A copy made in an otherwise Transparent file
+format whose markup has been designed to thwart or discourage
+subsequent modification by readers is not Transparent. A copy that is
+not ``Transparent'' is called ``Opaque''.
+
+<P>
+Examples of suitable formats for Transparent copies include plain
+ASCII without markup, Texinfo input format, <SPAN CLASS="logo,LaTeX">L<SUP><SMALL>A</SMALL></SUP>T<SMALL>E</SMALL>X</SPAN> input format, SGML
+or XML using a publicly available DTD, and standard-conforming simple
+HTML designed for human modification. Opaque formats include
+PostScript, PDF, proprietary formats that can be read and edited only
+by proprietary word processors, SGML or XML for which the DTD and/or
+processing tools are not generally available, and the
+machine-generated HTML produced by some word processors for output
+purposes only.
+
+<P>
+The ``Title Page'' means, for a printed book, the title page itself,
+plus such following pages as are needed to hold, legibly, the material
+this License requires to appear in the title page. For works in
+formats which do not have any title page as such, ``Title Page'' means
+the text near the most prominent appearance of the work's title,
+preceding the beginning of the body of the text.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node42.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node44.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node42.html">Preamble</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node44.html">B..2 Verbatim Copying</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node44.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>B..2 Verbatim Copying</title>
+<META NAME="description" CONTENT="B..2 Verbatim Copying">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node45.html">
+<LINK REL="previous" HREF="node43.html">
+<LINK REL="up" HREF="node41.html">
+<LINK REL="next" HREF="node45.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node43.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node45.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node43.html">B..1 Applicability and Definitions</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node45.html">B..3 Copying in Quantity</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000830000000000000000">
+B..2 Verbatim Copying</A>
+</H2>
+
+<P>
+You may copy and distribute the Document in any medium, either
+commercially or noncommercially, provided that this License, the
+copyright notices, and the license notice saying this License applies
+to the Document are reproduced in all copies, and that you add no other
+conditions whatsoever to those of this License. You may not use
+technical measures to obstruct or control the reading or further
+copying of the copies you make or distribute. However, you may accept
+compensation in exchange for copies. If you distribute a large enough
+number of copies you must also follow the conditions in section 3.
+
+<P>
+You may also lend copies, under the same conditions stated above, and
+you may publicly display copies.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node43.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node45.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node43.html">B..1 Applicability and Definitions</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node45.html">B..3 Copying in Quantity</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node45.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>B..3 Copying in Quantity</title>
+<META NAME="description" CONTENT="B..3 Copying in Quantity">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
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+<LINK REL="previous" HREF="node44.html">
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+<LINK REL="next" HREF="node46.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node44.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node46.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node44.html">B..2 Verbatim Copying</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node46.html">B..4 Modifications</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000840000000000000000">
+B..3 Copying in Quantity</A>
+</H2>
+
+<P>
+If you publish printed copies of the Document numbering more than 100,
+and the Document's license notice requires Cover Texts, you must enclose
+the copies in covers that carry, clearly and legibly, all these Cover
+Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
+the back cover. Both covers must also clearly and legibly identify
+you as the publisher of these copies. The front cover must present
+the full title with all words of the title equally prominent and
+visible. You may add other material on the covers in addition.
+Copying with changes limited to the covers, as long as they preserve
+the title of the Document and satisfy these conditions, can be treated
+as verbatim copying in other respects.
+
+<P>
+If the required texts for either cover are too voluminous to fit
+legibly, you should put the first ones listed (as many as fit
+reasonably) on the actual cover, and continue the rest onto adjacent
+pages.
+
+<P>
+If you publish or distribute Opaque copies of the Document numbering
+more than 100, you must either include a machine-readable Transparent
+copy along with each Opaque copy, or state in or with each Opaque copy
+a publicly-accessible computer-network location containing a complete
+Transparent copy of the Document, free of added material, which the
+general network-using public has access to download anonymously at no
+charge using public-standard network protocols. If you use the latter
+option, you must take reasonably prudent steps, when you begin
+distribution of Opaque copies in quantity, to ensure that this
+Transparent copy will remain thus accessible at the stated location
+until at least one year after the last time you distribute an Opaque
+copy (directly or through your agents or retailers) of that edition to
+the public.
+
+<P>
+It is requested, but not required, that you contact the authors of the
+Document well before redistributing any large number of copies, to give
+them a chance to provide you with an updated version of the Document.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node44.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node46.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node44.html">B..2 Verbatim Copying</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node46.html">B..4 Modifications</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node46.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>B..4 Modifications</title>
+<META NAME="description" CONTENT="B..4 Modifications">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node47.html">
+<LINK REL="previous" HREF="node45.html">
+<LINK REL="up" HREF="node41.html">
+<LINK REL="next" HREF="node47.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node45.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node47.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node45.html">B..3 Copying in Quantity</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node47.html">B..5 Combining Documents</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000850000000000000000">
+B..4 Modifications</A>
+</H2>
+
+<P>
+You may copy and distribute a Modified Version of the Document under
+the conditions of sections 2 and 3 above, provided that you release
+the Modified Version under precisely this License, with the Modified
+Version filling the role of the Document, thus licensing distribution
+and modification of the Modified Version to whoever possesses a copy
+of it. In addition, you must do these things in the Modified Version:
+
+<P>
+
+<UL>
+<LI>Use in the Title Page (and on the covers, if any) a title distinct
+ from that of the Document, and from those of previous versions
+ (which should, if there were any, be listed in the History section
+ of the Document). You may use the same title as a previous version
+ if the original publisher of that version gives permission.
+</LI>
+<LI>List on the Title Page, as authors, one or more persons or entities
+ responsible for authorship of the modifications in the Modified
+ Version, together with at least five of the principal authors of the
+ Document (all of its principal authors, if it has less than five).
+</LI>
+<LI>State on the Title page the name of the publisher of the
+ Modified Version, as the publisher.
+</LI>
+<LI>Preserve all the copyright notices of the Document.
+</LI>
+<LI>Add an appropriate copyright notice for your modifications
+ adjacent to the other copyright notices.
+</LI>
+<LI>Include, immediately after the copyright notices, a license notice
+ giving the public permission to use the Modified Version under the
+ terms of this License, in the form shown in the Addendum below.
+</LI>
+<LI>Preserve in that license notice the full lists of Invariant Sections
+ and required Cover Texts given in the Document's license notice.
+</LI>
+<LI>Include an unaltered copy of this License.
+</LI>
+<LI>Preserve the section entitled ``History'', and its title, and add to
+ it an item stating at least the title, year, new authors, and
+ publisher of the Modified Version as given on the Title Page. If
+ there is no section entitled ``History'' in the Document, create one
+ stating the title, year, authors, and publisher of the Document as
+ given on its Title Page, then add an item describing the Modified
+ Version as stated in the previous sentence.
+</LI>
+<LI>Preserve the network location, if any, given in the Document for
+ public access to a Transparent copy of the Document, and likewise
+ the network locations given in the Document for previous versions
+ it was based on. These may be placed in the ``History'' section.
+ You may omit a network location for a work that was published at
+ least four years before the Document itself, or if the original
+ publisher of the version it refers to gives permission.
+</LI>
+<LI>In any section entitled ``Acknowledgements'' or ``Dedications'',
+ preserve the section's title, and preserve in the section all the
+ substance and tone of each of the contributor acknowledgements
+ and/or dedications given therein.
+</LI>
+<LI>Preserve all the Invariant Sections of the Document,
+ unaltered in their text and in their titles. Section numbers
+ or the equivalent are not considered part of the section titles.
+</LI>
+<LI>Delete any section entitled ``Endorsements''. Such a section
+ may not be included in the Modified Version.
+</LI>
+<LI>Do not retitle any existing section as ``Endorsements''
+ or to conflict in title with any Invariant Section.
+
+<P>
+</LI>
+</UL>
+
+<P>
+If the Modified Version includes new front-matter sections or
+appendices that qualify as Secondary Sections and contain no material
+copied from the Document, you may at your option designate some or all
+of these sections as invariant. To do this, add their titles to the
+list of Invariant Sections in the Modified Version's license notice.
+These titles must be distinct from any other section titles.
+
+<P>
+You may add a section entitled ``Endorsements'', provided it contains
+nothing but endorsements of your Modified Version by various
+parties - for example, statements of peer review or that the text has
+been approved by an organization as the authoritative definition of a
+standard.
+
+<P>
+You may add a passage of up to five words as a Front-Cover Text, and a
+passage of up to 25 words as a Back-Cover Text, to the end of the list
+of Cover Texts in the Modified Version. Only one passage of
+Front-Cover Text and one of Back-Cover Text may be added by (or
+through arrangements made by) any one entity. If the Document already
+includes a cover text for the same cover, previously added by you or
+by arrangement made by the same entity you are acting on behalf of,
+you may not add another; but you may replace the old one, on explicit
+permission from the previous publisher that added the old one.
+
+<P>
+The author(s) and publisher(s) of the Document do not by this License
+give permission to use their names for publicity for or to assert or
+imply endorsement of any Modified Version.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node45.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node47.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node45.html">B..3 Copying in Quantity</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node47.html">B..5 Combining Documents</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node47.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>B..5 Combining Documents</title>
+<META NAME="description" CONTENT="B..5 Combining Documents">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node48.html">
+<LINK REL="previous" HREF="node46.html">
+<LINK REL="up" HREF="node41.html">
+<LINK REL="next" HREF="node48.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node46.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node48.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node46.html">B..4 Modifications</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node48.html">B..6 Collections of Documents</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000860000000000000000">
+B..5 Combining Documents</A>
+</H2>
+
+<P>
+You may combine the Document with other documents released under this
+License, under the terms defined in section 4 above for modified
+versions, provided that you include in the combination all of the
+Invariant Sections of all of the original documents, unmodified, and
+list them all as Invariant Sections of your combined work in its
+license notice.
+
+<P>
+The combined work need only contain one copy of this License, and
+multiple identical Invariant Sections may be replaced with a single
+copy. If there are multiple Invariant Sections with the same name but
+different contents, make the title of each such section unique by
+adding at the end of it, in parentheses, the name of the original
+author or publisher of that section if known, or else a unique number.
+Make the same adjustment to the section titles in the list of
+Invariant Sections in the license notice of the combined work.
+
+<P>
+In the combination, you must combine any sections entitled ``History''
+in the various original documents, forming one section entitled
+``History''; likewise combine any sections entitled ``Acknowledgements'',
+and any sections entitled ``Dedications''. You must delete all sections
+entitled ``Endorsements.''
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node46.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node48.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node46.html">B..4 Modifications</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node48.html">B..6 Collections of Documents</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node48.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>B..6 Collections of Documents</title>
+<META NAME="description" CONTENT="B..6 Collections of Documents">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node49.html">
+<LINK REL="previous" HREF="node47.html">
+<LINK REL="up" HREF="node41.html">
+<LINK REL="next" HREF="node49.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node47.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node49.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node47.html">B..5 Combining Documents</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node49.html">B..7 Aggregation With Independent</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000870000000000000000">
+B..6 Collections of Documents</A>
+</H2>
+
+<P>
+You may make a collection consisting of the Document and other documents
+released under this License, and replace the individual copies of this
+License in the various documents with a single copy that is included in
+the collection, provided that you follow the rules of this License for
+verbatim copying of each of the documents in all other respects.
+
+<P>
+You may extract a single document from such a collection, and distribute
+it individually under this License, provided you insert a copy of this
+License into the extracted document, and follow this License in all
+other respects regarding verbatim copying of that document.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node47.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node49.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node47.html">B..5 Combining Documents</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node49.html">B..7 Aggregation With Independent</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node49.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>B..7 Aggregation With Independent Works</title>
+<META NAME="description" CONTENT="B..7 Aggregation With Independent Works">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node50.html">
+<LINK REL="previous" HREF="node48.html">
+<LINK REL="up" HREF="node41.html">
+<LINK REL="next" HREF="node50.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node48.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node50.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node48.html">B..6 Collections of Documents</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node50.html">B..8 Translation</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000880000000000000000">
+B..7 Aggregation With Independent Works</A>
+</H2>
+
+<P>
+A compilation of the Document or its derivatives with other separate
+and independent documents or works, in or on a volume of a storage or
+distribution medium, does not as a whole count as a Modified Version
+of the Document, provided no compilation copyright is claimed for the
+compilation. Such a compilation is called an ``aggregate'', and this
+License does not apply to the other self-contained works thus compiled
+with the Document, on account of their being thus compiled, if they
+are not themselves derivative works of the Document.
+
+<P>
+If the Cover Text requirement of section 3 is applicable to these
+copies of the Document, then if the Document is less than one quarter
+of the entire aggregate, the Document's Cover Texts may be placed on
+covers that surround only the Document within the aggregate.
+Otherwise they must appear on covers around the whole aggregate.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node48.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node50.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node48.html">B..6 Collections of Documents</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node50.html">B..8 Translation</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node5.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>1.3 What is ZEO?</title>
+<META NAME="description" CONTENT="1.3 What is ZEO?">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node6.html">
+<LINK REL="previous" HREF="node4.html">
+<LINK REL="up" HREF="node2.html">
+<LINK REL="next" HREF="node6.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node4.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node2.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node6.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node4.html">1.2 OODBs vs. Relational</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node2.html">1 Introduction</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node6.html">1.4 About this guide</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000230000000000000000">
+1.3 What is ZEO?</A>
+</H2>
+
+<P>
+The ZODB comes with a few different classes that implement the
+<tt class="class">Storage</tt> interface. Such classes handle the job of
+writing out Python objects to a physical storage medium, which can be
+a disk file (the <tt class="class">FileStorage</tt> class), a BerkeleyDB file
+(<tt class="class">BerkeleyStorage</tt>), a relational database
+(<tt class="class">DCOracleStorage</tt>), or some other medium. ZEO adds
+<tt class="class">ClientStorage</tt>, a new <tt class="class">Storage</tt> that doesn't write to
+physical media but just forwards all requests across a network to a
+server. The server, which is running an instance of the
+<tt class="class">StorageServer</tt> class, simply acts as a front-end for some
+physical <tt class="class">Storage</tt> class. It's a fairly simple idea, but as
+we'll see later on in this document, it opens up many possibilities.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node4.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node2.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node6.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node4.html">1.2 OODBs vs. Relational</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node2.html">1 Introduction</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node6.html">1.4 About this guide</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node50.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>B..8 Translation</title>
+<META NAME="description" CONTENT="B..8 Translation">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node51.html">
+<LINK REL="previous" HREF="node49.html">
+<LINK REL="up" HREF="node41.html">
+<LINK REL="next" HREF="node51.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node49.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node51.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node49.html">B..7 Aggregation With Independent</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node51.html">B..9 Termination</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000890000000000000000">
+B..8 Translation</A>
+</H2>
+
+<P>
+Translation is considered a kind of modification, so you may
+distribute translations of the Document under the terms of section 4.
+Replacing Invariant Sections with translations requires special
+permission from their copyright holders, but you may include
+translations of some or all Invariant Sections in addition to the
+original versions of these Invariant Sections. You may include a
+translation of this License provided that you also include the
+original English version of this License. In case of a disagreement
+between the translation and the original English version of this
+License, the original English version will prevail.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node49.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node51.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node49.html">B..7 Aggregation With Independent</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node51.html">B..9 Termination</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node51.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>B..9 Termination</title>
+<META NAME="description" CONTENT="B..9 Termination">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node52.html">
+<LINK REL="previous" HREF="node50.html">
+<LINK REL="up" HREF="node41.html">
+<LINK REL="next" HREF="node52.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node50.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node52.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node50.html">B..8 Translation</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node52.html">B..10 Future Revisions of</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION0008100000000000000000">
+B..9 Termination</A>
+</H2>
+
+<P>
+You may not copy, modify, sublicense, or distribute the Document except
+as expressly provided for under this License. Any other attempt to
+copy, modify, sublicense or distribute the Document is void, and will
+automatically terminate your rights under this License. However,
+parties who have received copies, or rights, from you under this
+License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node50.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node52.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node50.html">B..8 Translation</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node52.html">B..10 Future Revisions of</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node52.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>B..10 Future Revisions of This Licence</title>
+<META NAME="description" CONTENT="B..10 Future Revisions of This Licence">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node53.html">
+<LINK REL="previous" HREF="node51.html">
+<LINK REL="up" HREF="node41.html">
+<LINK REL="next" HREF="node53.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node51.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node53.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node51.html">B..9 Termination</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node53.html">ADDENDUM: How to use</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION0008110000000000000000">
+B..10 Future Revisions of This Licence</A>
+</H2>
+
+<P>
+The Free Software Foundation may publish new, revised versions
+of the GNU Free Documentation License from time to time. Such new
+versions will be similar in spirit to the present version, but may
+differ in detail to address new problems or concerns. See
+<a class="url" href="http://www.gnu.org/copyleft/">http://www.gnu.org/copyleft/</a>.
+
+<P>
+Each version of the License is given a distinguishing version number.
+If the Document specifies that a particular numbered version of this
+License "or any later version" applies to it, you have the option of
+following the terms and conditions either of that specified version or
+of any later version that has been published (not as a draft) by the
+Free Software Foundation. If the Document does not specify a version
+number of this License, you may choose any version ever published (not
+as a draft) by the Free Software Foundation.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node51.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node53.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node51.html">B..9 Termination</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node53.html">ADDENDUM: How to use</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node53.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>ADDENDUM: How to use this License for your documents</title>
+<META NAME="description" CONTENT="ADDENDUM: How to use this License for your documents">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="previous" HREF="node52.html">
+<LINK REL="up" HREF="node41.html">
+<LINK REL="next" href="about.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node52.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A href="about.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node52.html">B..10 Future Revisions of</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" href="about.html">About this document ...</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION0008120000000000000000">
+ADDENDUM: How to use this License for your documents</A>
+</H2>
+
+<P>
+To use this License in a document you have written, include a copy of
+the License in the document and put the following copyright and
+license notices just after the title page:
+
+<P>
+<P>
+<BLOCKQUOTE>Copyright <SPAN CLASS="MATH"><IMG
+ WIDTH="20" HEIGHT="29" ALIGN="MIDDLE" BORDER="0"
+ SRC="img1.gif"
+ ALT="$\copyright$"></SPAN> YEAR YOUR NAME.
+ Permission is granted to copy, distribute and/or modify this document
+ under the terms of the GNU Free Documentation License, Version 1.1
+ or any later version published by the Free Software Foundation;
+ with the Invariant Sections being LIST THEIR TITLES, with the
+ Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
+ A copy of the license is included in the section entitled ``GNU
+ Free Documentation License''.
+</BLOCKQUOTE>
+<P>
+
+<P>
+If you have no Invariant Sections, write ``with no Invariant Sections''
+instead of saying which ones are invariant. If you have no
+Front-Cover Texts, write ``no Front-Cover Texts'' instead of
+``Front-Cover Texts being LIST''; likewise for Back-Cover Texts.
+
+<P>
+If your document contains nontrivial examples of program code, we
+recommend releasing these examples in parallel under your choice of
+free software license, such as the GNU General Public License,
+to permit their use in free software.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node52.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node41.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A href="about.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node52.html">B..10 Future Revisions of</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node41.html">B. GNU Free Documentation</A>
+<b class="navlabel">Next:</b> <a class="sectref" href="about.html">About this document ...</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node6.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>1.4 About this guide</title>
+<META NAME="description" CONTENT="1.4 About this guide">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node7.html">
+<LINK REL="previous" HREF="node5.html">
+<LINK REL="up" HREF="node2.html">
+<LINK REL="next" HREF="node7.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node5.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node2.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node7.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node5.html">1.3 What is ZEO?</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node2.html">1 Introduction</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node7.html">1.5 Acknowledgements</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000240000000000000000">
+1.4 About this guide</A>
+</H2>
+
+<P>
+The primary author of this guide works on a project which uses the
+ZODB and ZEO as its primary storage technology. We use the ZODB to
+store process runs and operations, a catalog of available processes,
+user information, accounting information, and other data. Part of the
+goal of writing this document is to make our experience more widely
+available. A few times we've spent hours or even days trying to
+figure out a problem, and this guide is an attempt to gather up the
+knowledge we've gained so that others don't have to make the same
+mistakes we did while learning.
+
+<P>
+This document will always be a work in progress. If you wish to
+suggest clarifications or additional topics, please send your comments to
+<span class="email">akuchlin@mems-exchange.org</span>.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node5.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node2.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node7.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node5.html">1.3 What is ZEO?</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node2.html">1 Introduction</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node7.html">1.5 Acknowledgements</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node7.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>1.5 Acknowledgements</title>
+<META NAME="description" CONTENT="1.5 Acknowledgements">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="previous" HREF="node6.html">
+<LINK REL="up" HREF="node2.html">
+<LINK REL="next" HREF="node8.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node6.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node2.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node8.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node6.html">1.4 About this guide</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node2.html">1 Introduction</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000250000000000000000">
+1.5 Acknowledgements</A>
+</H2>
+
+<P>
+I'd like to thank the people who've pointed out inaccuracies and bugs,
+offered suggestions on the text, or proposed new topics that should be
+covered: Jeff Bauer, Willem Broekema, Thomas Guettler,
+Chris McDonough, George Runyan.
+
+<P>
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node6.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node2.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node8.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node6.html">1.4 About this guide</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node2.html">1 Introduction</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node8.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>2 ZODB Programming</title>
+<META NAME="description" CONTENT="2 ZODB Programming">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" href="zeo.html">
+<LINK REL="previous" HREF="node2.html">
+<LINK REL="up" HREF="zodb.html">
+<LINK REL="next" HREF="node9.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node7.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node9.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node7.html">1.5 Acknowledgements</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node9.html">2.1 Installing ZODB</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H1><A NAME="SECTION000300000000000000000">
+2 ZODB Programming</A>
+</H1>
+
+<P>
+
+<p><hr>
+<!--Table of Child-Links-->
+<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></a>
+
+<UL>
+<LI><A href="node9.html">2.1 Installing ZODB</a>
+<UL>
+<LI><A href="node10.html">2.1.1 Requirements</a>
+<LI><A href="node11.html">2.1.2 Installing the Packages</a>
+</ul>
+<LI><A href="node12.html">2.2 How ZODB Works</a>
+<LI><A href="node13.html">2.3 Opening a ZODB</a>
+<LI><A href="node14.html">2.4 Writing a Persistent Class</a>
+<LI><A href="node15.html">2.5 Rules for Writing Persistent Classes</a>
+<UL>
+<LI><A href="node16.html">2.5.1 Modifying Mutable Objects</a>
+<LI><A href="node17.html">2.5.2 Some Special Methods Don't Work</a>
+<LI><A href="node18.html">2.5.3 Fixing <tt class="function">isinstance</tt> and <tt class="function">issubclass</tt></a>
+<LI><A href="node19.html">2.5.4 <tt class="method">__getattr__</tt>, <tt class="method">__delattr__</tt>, and <tt class="method">__setattr__</tt></a>
+</ul>
+<LI><A href="node20.html">2.6 Writing Persistent Classes</a>
+<UL>
+<LI><A href="node21.html">2.6.1 Changing Instance Attributes</a>
+</ul></ul>
+<!--End of Table of Child-Links-->
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node7.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node9.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node7.html">1.5 Acknowledgements</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node9.html">2.1 Installing ZODB</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/node9.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>2.1 Installing ZODB</title>
+<META NAME="description" CONTENT="2.1 Installing ZODB">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node12.html">
+<LINK REL="previous" HREF="node8.html">
+<LINK REL="up" HREF="node8.html">
+<LINK REL="next" HREF="node10.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node8.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node8.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node10.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node10.html">2.1.1 Requirements</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H2><A NAME="SECTION000310000000000000000">
+2.1 Installing ZODB</A>
+</H2>
+
+<P>
+The ZODB forms part of Zope, but it's difficult and somewhat painful
+to extract the bits from Zope needed to support just the ZODB.
+Therefore I've assembled a distribution containing only the packages
+required to use the ZODB and ZEO, so you can install it and start
+programming right away.
+
+<P>
+To download the distribution, go to my ZODB page at
+<a class="url" href="http://www.amk.ca/zodb/">http://www.amk.ca/zodb/</a>.
+The distribution is still experimental, so don't be surprised if the
+installation process runs into problems. Please inform me of any
+difficulties you encounter.
+
+<P>
+
+<p><hr>
+<!--Table of Child-Links-->
+<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></a>
+
+<UL>
+<LI><A href="node10.html">2.1.1 Requirements</a>
+<LI><A href="node11.html">2.1.2 Installing the Packages</a>
+</ul>
+<!--End of Table of Child-Links-->
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node8.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="node8.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node10.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="node8.html">2 ZODB Programming</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node10.html">2.1.1 Requirements</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/zeo.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>3 ZEO</title>
+<META NAME="description" CONTENT="3 ZEO">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" HREF="node31.html">
+<LINK REL="previous" HREF="node8.html">
+<LINK REL="up" HREF="zodb.html">
+<LINK REL="next" HREF="node23.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node21.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node23.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node21.html">2.6.1 Changing Instance Attributes</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node23.html">3.1 How ZEO Works</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<H1><A NAME="SECTION000400000000000000000"> </A>
+<BR>
+3 ZEO
+</H1>
+
+<P>
+
+<p><hr>
+<!--Table of Child-Links-->
+<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></a>
+
+<UL>
+<LI><A href="node23.html">3.1 How ZEO Works</a>
+<LI><A href="node24.html">3.2 Installing ZEO</a>
+<UL>
+<LI><A href="node25.html">3.2.1 Requirements</a>
+<LI><A href="node26.html">3.2.2 Installation</a>
+</ul>
+<LI><A href="node27.html">3.3 Configuring and Running a ZEO Server</a>
+<LI><A href="node28.html">3.4 Testing the ZEO Installation</a>
+<LI><A href="node29.html">3.5 ZEO Programming Notes</a>
+<LI><A href="node30.html">3.6 Sample Application: chatter.py</a>
+</ul>
+<!--End of Table of Child-Links-->
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><A HREF="node21.html"><img src="/python/writing/icons/previous.gif"
+ border="0" height="32"
+ alt="Previous Page" width="32"></A></td>
+<td><A HREF="zodb.html"><img src="/python/writing/icons/up.gif"
+ border="0" height="32"
+ alt="Up One Level" width="32"></A></td>
+<td><A HREF="node23.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Previous:</b> <a class="sectref" HREF="node21.html">2.6.1 Changing Instance Attributes</A>
+<b class="navlabel">Up:</b> <a class="sectref" HREF="zodb.html">ZODB/ZEO Programming Guide</A>
+<b class="navlabel">Next:</b> <a class="sectref" HREF="node23.html">3.1 How ZEO Works</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>
=== StandaloneZODB/Doc/guide/zodb/zodb.css 1.1 => 1.2 ===
+ * The first part of this is the standard CSS generated by LaTeX2HTML,
+ * with the "empty" declarations removed.
+ */
+
+/* Century Schoolbook font is very similar to Computer Modern Math: cmmi */
+.math { font-family: "Century Schoolbook", serif; }
+.math i { font-family: "Century Schoolbook", serif;
+ font-weight: bold }
+.boldmath { font-family: "Century Schoolbook", serif;
+ font-weight: bold }
+
+/*
+ * Implement both fixed-size and relative sizes.
+ *
+ * I think these can be safely removed, as it doesn't appear that
+ * LaTeX2HTML ever generates these, even though these are carried
+ * over from the LaTeX2HTML stylesheet.
+ */
+small.xtiny { font-size : xx-small; }
+small.tiny { font-size : x-small; }
+small.scriptsize { font-size : smaller; }
+small.footnotesize { font-size : small; }
+big.xlarge { font-size : large; }
+big.xxlarge { font-size : x-large; }
+big.huge { font-size : larger; }
+big.xhuge { font-size : xx-large; }
+
+/*
+ * Document-specific styles come next;
+ * these are added for the Python documentation.
+ *
+ * Note that the size specifications for the H* elements are because
+ * Netscape on Solaris otherwise doesn't get it right; they all end up
+ * the normal text size.
+ */
+
+body { color: #000000;
+ background-color: #ffffff; }
+
+a:active { color: #ff0000; }
+a:visited { color: #551a8b; }
+a:link { color: #0000bb; }
+
+h1, h2, h3, h4, h5, h6 { font-family: avantgarde, sans-serif;
+ font-weight: bold; }
+h1 { font-size: 180%; }
+h2 { font-size: 150%; }
+h3, h4 { font-size: 120%; }
+code, tt { font-family: lucida typewriter, lucidatypewriter,
+ monospace; }
+var { font-family: times, serif;
+ font-style: italic;
+ font-weight: normal; }
+
+.typelabel { font-family: lucida, sans-serif; }
+
+.navigation td { background-color: #99ccff;
+ font-weight: bold;
+ font-family: avantgarde, sans-serif;
+ font-size: 110%; }
+
+.release-info { font-style: italic; }
+
+.titlegraphic { vertical-align: top; }
+
+.verbatim { color: #00008b;
+ font-family: lucida typewriter, lucidatypewriter,
+ monospace; }
+
+.grammar { background-color: #99ccff;
+ margin-right: 0.5in;
+ padding: 0.05in; }
+.productions { background-color: #bbeeff; }
+.productions table { vertical-align: baseline; }
+.grammar-footer { padding: 0.05in;
+ font-size: 85%; }
+
+.email { font-family: avantgarde, sans-serif; }
+.mailheader { font-family: avantgarde, sans-serif; }
+.mimetype { font-family: avantgarde, sans-serif; }
+.newsgroup { font-family: avantgarde, sans-serif; }
+.url { font-family: avantgarde, sans-serif; }
+.file { font-family: avantgarde, sans-serif; }
+
+.tableheader { background-color: #99ccff;
+ font-family: avantgarde, sans-serif; }
+
+.refcount-info { font-style: italic; }
+.refcount-info .value { font-weight: bold;
+ color: #006600; }
+
+/*
+ * Some decoration for the "See also:" blocks, in part inspired by some of
+ * the styling on Lars Marius Garshol's XSA pages.
+ * (The blue in the navigation bars is #99CCFF.)
+ */
+.seealso { background-color: #fffaf0;
+ border: thin solid black;
+ padding: 4pt; }
+
+.seealso .heading { font-size: 110%; }
+
+/*
+ * Class 'availability' is used for module availability statements at
+ * the top of modules.
+ */
+.availability .platform { font-weight: bold; }
=== StandaloneZODB/Doc/guide/zodb/zodb.html 1.1 => 1.2 ===
+<html>
+<head>
+<title>ZODB/ZEO Programming Guide</title>
+<META NAME="description" CONTENT="ZODB/ZEO Programming Guide">
+<META NAME="keywords" CONTENT="zodb">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<meta http-equiv="Content-Type" content="text/html; charset=">
+<link rel="STYLESHEET" href="zodb.css">
+<link rel="first" href="zodb.html">
+<link rel="contents" href="contents.html" title="Contents">
+
+<LINK REL="next" href="contents.html">
+</head>
+<body>
+<DIV CLASS="navigation">
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><A href="contents.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Next:</b> <a class="sectref" href="contents.html">Contents</A>
+<br><hr>
+</DIV>
+<!--End of Navigation Panel-->
+
+<div class="titlepage">
+<center>
+<h1>ZODB/ZEO Programming Guide</h1>
+<p><b><font size="+2">A.M. Kuchling</font></b></p>
+<p>akuchlin@mems-exchange.org</p>
+<p><strong>Release 0.03</strong><br>
+<strong>February 8, 2002</strong></p>
+<p>
+</center>
+</div>
+
+<p><hr>
+<!--Table of Child-Links-->
+<A NAME="CHILD_LINKS"></a>
+
+<UL>
+<LI><A href="contents.html">Contents</a>
+<LI><A href="node2.html">1 Introduction</a>
+<UL>
+<LI><A href="node3.html">1.1 What is the ZODB?</a>
+<LI><A href="node4.html">1.2 OODBs vs. Relational DBs</a>
+<LI><A href="node5.html">1.3 What is ZEO?</a>
+<LI><A href="node6.html">1.4 About this guide</a>
+<LI><A href="node7.html">1.5 Acknowledgements</a>
+</ul>
+<LI><A href="node8.html">2 ZODB Programming</a>
+<UL>
+<LI><A href="node9.html">2.1 Installing ZODB</a>
+<UL>
+<LI><A href="node10.html">2.1.1 Requirements</a>
+<LI><A href="node11.html">2.1.2 Installing the Packages</a>
+</ul>
+<LI><A href="node12.html">2.2 How ZODB Works</a>
+<LI><A href="node13.html">2.3 Opening a ZODB</a>
+<LI><A href="node14.html">2.4 Writing a Persistent Class</a>
+<LI><A href="node15.html">2.5 Rules for Writing Persistent Classes</a>
+<UL>
+<LI><A href="node16.html">2.5.1 Modifying Mutable Objects</a>
+<LI><A href="node17.html">2.5.2 Some Special Methods Don't Work</a>
+<LI><A href="node18.html">2.5.3 Fixing <tt class="function">isinstance</tt> and <tt class="function">issubclass</tt></a>
+<LI><A href="node19.html">2.5.4 <tt class="method">__getattr__</tt>, <tt class="method">__delattr__</tt>, and <tt class="method">__setattr__</tt></a>
+</ul>
+<LI><A href="node20.html">2.6 Writing Persistent Classes</a>
+<UL>
+<LI><A href="node21.html">2.6.1 Changing Instance Attributes</a>
+</ul>
+</ul>
+<LI><A href="zeo.html">3 ZEO</a>
+<UL>
+<LI><A href="node23.html">3.1 How ZEO Works</a>
+<LI><A href="node24.html">3.2 Installing ZEO</a>
+<UL>
+<LI><A href="node25.html">3.2.1 Requirements</a>
+<LI><A href="node26.html">3.2.2 Installation</a>
+</ul>
+<LI><A href="node27.html">3.3 Configuring and Running a ZEO Server</a>
+<LI><A href="node28.html">3.4 Testing the ZEO Installation</a>
+<LI><A href="node29.html">3.5 ZEO Programming Notes</a>
+<LI><A href="node30.html">3.6 Sample Application: chatter.py</a>
+</ul>
+<LI><A href="node31.html">4 Transactions and Versioning</a>
+<UL>
+<LI><A href="node32.html">4.1 Subtransactions</a>
+<LI><A href="node33.html">4.2 Undoing Changes</a>
+<LI><A href="node34.html">4.3 Versions</a>
+<LI><A href="node35.html">4.4 Multithreaded ZODB Programs</a>
+</ul>
+<LI><A href="node36.html">5 Related Modules</a>
+<UL>
+<LI><A href="node37.html">5.1 <tt class="module">ZODB.PersistentMapping</tt></a>
+<LI><A href="node38.html">5.2 <tt class="module">ZODB.PersistentList</tt></a>
+<LI><A href="node39.html">5.3 B-tree Modules</a>
+</ul>
+<LI><A href="node40.html">A. Resources</a>
+<LI><A href="node41.html">B. GNU Free Documentation License</a>
+<UL>
+<LI><A href="node42.html">Preamble</a>
+<LI><A href="node43.html">B..1 Applicability and Definitions</a>
+<LI><A href="node44.html">B..2 Verbatim Copying</a>
+<LI><A href="node45.html">B..3 Copying in Quantity</a>
+<LI><A href="node46.html">B..4 Modifications</a>
+<LI><A href="node47.html">B..5 Combining Documents</a>
+<LI><A href="node48.html">B..6 Collections of Documents</a>
+<LI><A href="node49.html">B..7 Aggregation With Independent Works</a>
+<LI><A href="node50.html">B..8 Translation</a>
+<LI><A href="node51.html">B..9 Termination</a>
+<LI><A href="node52.html">B..10 Future Revisions of This Licence</a>
+<LI><A href="node53.html">ADDENDUM: How to use this License for your documents</a>
+</ul>
+<LI><A href="about.html">About this document ...</a>
+</ul>
+<!--End of Table of Child-Links-->
+
+<DIV CLASS="navigation">
+<p><hr>
+<table align="center" width="100%" cellpadding="0" cellspacing="2">
+<tr>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><A href="contents.html"><img src="/python/writing/icons/next.gif"
+ border="0" height="32"
+ alt="Next Page" width="32"></A></td>
+<td align="center" width="100%">ZODB/ZEO Programming Guide</td>
+<td><A href="contents.html"><img src="/python/writing/icons/contents.gif"
+ border="0" height="32"
+ alt="Contents" width="32"></A></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+<td><img src="/python/writing/icons/blank.gif"
+ border="0" height="32"
+ alt="" width="32"></td>
+</tr></table>
+<b class="navlabel">Next:</b> <a class="sectref" href="contents.html">Contents</A>
+<hr>
+<span class="release-info">Release 0.03, documentation updated on February 8, 2002.</span>
+</DIV>
+<!--End of Navigation Panel-->
+
+</BODY>
+</HTML>