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RE: [Zope] ZCatalog searching questions
by Alexander Staubo 14 Oct '99

14 Oct '99

I just came across this post of yours. Curious: Have you guys looked at ternary search trees [1] as an alternative dictionary algorithm? Compared to B-trees and their variants, ternary trees are extremely space-efficient, and lend themselves greatly to partial searching -- such as finding words starting with a certain substring, or pure wildcard matches -- and nearest-neighbour searching. They're not just simple in structure, they're lightning fast, too: Searching for a string of length k in a tree containing n strings will require at most O(log n+k) comparisons. A semirecent article [2] explained the concept in detail. I've successfully employed them and can personally verify their usefulness and speed. Because they're light, the I/O required to process searches is negible compared to other methods such as hash tables or binary trees (and their variants). Unlike binary trees, non-recursive search functions are just as simple to write as recursive ones (the only stack space theoretically needed is the search string and your node representation); balancing is generally not needed, although it is possible to enforce; finally, ternary trees have low overhead for insertion and successful searches. Ternary trees get their names from having three children per node, contrary to the binary tree family, which use two. Each node contains a "split character" and three "low", "equal", and "high" child pointers. The split character is an 8-bit (or 16-bit UNICODE) character value. Let's say we store the words FOO, FRED, FRUIT, ZOPE, and BAR, in that order. The three built is thus (I use "." to denote a null splitchar): F /|\ B O \ | |\ \ A O R \ | | | \ R . E \ | |\ Z . D U | | | O . I | | P T | | E . | . Let's say we're searching for the word "FRUIT\0" (a terminating null character is used to avoid matching with stuff like "FRUITCAKE"; if we leave out the terminating null, this becomes a partial-match search). First, we find the root node, "F". It's equal to our starting character, so we increment our character pointer and go to the node's "equal" child, "O". R > O, so we proceed to the "high" child and find "R". R == R, so we increment our pointer, proceed to the "equal" child, and find "E". U > E, so we proceed to the "high" child, and we find "U". U == U, so we increment our pointer, and so on. We know we've found a singular entry for "FRUIT" because the final splitchar is null. How to traverse, and insert into, this tree should be obvious to anyone. Notice how easily partial/expression searches can be done, since the tree itself lends itself to string-like operations. .. [1] "Fast Algorithms for Sorting and Searching Strings", Jon Bentley/Bob Sedgewick, Proceedings of the 8th Annual ACM-SIAM Symposium on Discrete Algorithms, January 1997. .. [2] Ternary Search Trees, Jon Bentley/Bob Sedgewick, Dr. Dobb's Journal, April 1998. I wrote a ternary tree module in Python a while ago. You can get it here: http://www.mop.no/~alex/download/pytrees.tgz. It does not serve to show any benefits in speed or footprint: Python's memory management, string handling, and garbage collection facilities are not tailored to handle this stuff efficiently, so in Python binary trees have the upper hand. It should, however, serve as a nice demo of the algorithm itself. -- Alexander Staubo http://alex.mop.no/ "In the end, we all assume room temperature." --John Maynard Keynes > -----Original Message----- > From: Michel Pelletier [mailto:michel@digicool.com] > Sent: 30. september 1999 07:55 > To: Dave Kimmel > Cc: 'zope(a)zope.org' > Subject: Re: [Zope] ZCatalog searching questions > > > Dave Kimmel wrote: > > > > Hello all > > > > I'm trying to re-implement the internal policy manual here > at work using > > Zope (it's currently hyperlinked WordPerfect documents), > and after demoing > > it to management there are now two things I need to solve > with the search > > feature. > > > > First, is there any way I can search by regular expression > or search for > > part of a word? Specifically, I need to search the content > of a bunch of > > DTML Documents (these only contain the text of the policies > and references > > to standard_html_header and standard_html_footer) for > partial word matches. > > For example, "vac" needs to match "vacation", "vacations", > "vaccination", > > etc. > > No. This is a vastly harder problem than it sounds like. Think of a > real book index, how would arrange the index 'keys' so that > you could do > something like '*ing'? The immediate solution is to store two > 'sub-keys' per word, one with the word forward 'walking' and one with > the word backwards ('gniklaw'). This way you can say walk* > or *ing and > get walking in both instances (and 'walked', 'zopeing' etc...). > > The problem is now your 'lexicon' has doubled in size. Try > it yourself. > > Some people thing, 'why not use re (the Python regex > module)?', because > searching like '*ing' would require iterating over all the keys, a > linear search like this could take multiple order of maginitude more > time than a non-regex search. > > There is a pretty good compromise solution called n-grams, > but they also > result in a lexicon increase, and a much more complicated > algorithm. I > can refer you to a good book that describes them. > > The recent abstraction of the Catalog's 'lexicon' will > eventually allow > you plug custom lexicon objects into the catalog, giving you hooks to > impliment this service yourself, if someone doesn't pay us to do it > first. > > > Second, is there any way to use a list of synonyms when > searching? For > > example, a search for "headstone" should also search for > "monument" and > > "gravestone", and likewise a search for "gravestone" should > also search for > > "monument" and "headstone". > > Yes. The 'lexicon' has a hardwired 'synonym and stopword' > dictionary in > lib/python/SearchIndex/Lexicon.py. This is also projected to be > improved by allowing through-the-web lexicon managment (like > specifying > stopwords and synonmys). Someone also suggested interfacing > it to some > kind of synonym database, you'd have to search through the arvhives to > find the reference. > > > Am I asking too much of this? Should I be buying a Python > book and adding > > this functionality myself? Should I be using something > other than ZCatalog? > > Should I be using something other than Zope? (Please say > no, I happen to > > like Zope!) > > Go for it, but don't give up on ZCatalog or Zope, I'd be surprised if > you found fully featured regex searching in another package that would > take less of a headache to use than just implimenting a simple > 'reversed' lexicon that let's you do globbing (like dos > wildcard, no *s > in the middle of words, etc.). > > -Michel > > > Thank you! > > -- Dave Kimmel > > Systems Analyst > > Office of the Public Trustee, Alberta Justice > > _______________________________________________ > Zope maillist - Zope(a)zope.org > http://www.zope.org/mailman/listinfo/zope > > (Related lists - please, no cross posts or HTML encoding! > > To receive general Zope announcements, see: > http://www.zope.org/mailman/listinfo/zope-announce > > For developer-specific issues, zope-dev(a)zope.org - > http://www.zope.org/mailman/listinfo/zope-dev ) >

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RE: [Zope] Le Zope de Microsoft
by Jay, Dylan 14 Oct '99

14 Oct '99

Some very interesting ideas in there. Its a pigs breakfast just like most MS stuff but interesting anyway. I like the idea of using an SQL like language to query the heirachical DB. Also the tight intergration of synchronous and asynchronous (email) events/communications into the "web store" is something I've thought is importent for awhile. -----Original Message----- From: Gerard Mulot [mailto:vanisoft@wanadoo.fr] Sent: Wednesday, October 13, 1999 18:18 To: zope(a)zope.org Subject: [Zope] Le Zope de Microsoft Le Zope de Microsoft http://msdn.microsoft.com/isapi/msdnlib2.idc?theURL=/library/backgrnd/html/w ebstorewp.htm regards Gerard Mulot

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FYI: Zope Weekly News
by Amos Latteier 13 Oct '99

13 Oct '99

Hi, Yet another active week in Zopeland. The Zope community continues to churn out great ideas and software at an incredible rate. Its very exciting to watch existing Zope projects like Squishdot mature and new projects like PythonMethods spring up. * Ng Pheng Siong posted his additions to ZServer which allow it to do SSL with the M2Crypto Python package. Very cool indeed! http://www.zope.org/pipermail/zope-dev/1999-October/001803.html http://www.post1.com/home/ngps/m2 * Bill Anderson updated his Knowledge Kit to version 1.6.3. Knowledge Kit is a Zope Product for creating knowledge bases. http://www.zope.org/Members/Bill/Products/KnowledgeKit * Butch Landingin released Squishdot 0.3.0 Squishdot is a very popular Zope Product for running Slashdot-like discussion sites. Many cool Zope sites including Technocrat.net run Squishdot. http://www.squishdot.org/ http://www.zope.org/pipermail/zope/1999-October/011663.html * Following up on his excellent ZODB work last week, this week Ty Sarna posted a CompressedStorage class which can be layered over another ZODB storage to provide pickle compression. http://www.zope.org/Members/tsarna/CompressedStorage/Announcement * The tireless Jeff Rush updated his Zope RPMS for Zope 2.0.1. He also compiled the ZODBC database adapter for use with Solid Technology's commercial SQL database product (v2.3), under Linux. http://starship.python.net/crew/jrush/Zope/ http://starship.python.net/crew/jrush/Zope/Zope2.html#ZODBCDA * Evan Simpson updated Python Methods to version 0.1.4 http://www.zope.org/Members/4am/PythonMethod * Stuart Bishop released Logger 1.0.1 which allows you to write to Zope's log files from DTML. This can be quite useful for debugging and error logging. http://www.zope.org/Members/Zen/Logger * Amos Latteier posted a XML-RPC How-To. This link immediately showed up to www.scripting.com and www.xmlrpc.com. http://www.zope.org/Members/Amos/XML-RPC * Jason M. Thaxter pointed out that Zope is mentioned in a Tim O'Reilly piece. http://xml.com/pub/1999/10/tokyo.html * Jonathan Corbet and Roman Milner pointed out that www.HireTechs.com has launched an auction site using Zope, though they do not identify the site as Zope-powered. http://www.newsalert.com/bin/story?StoryId=Cn_1SqbKbytaXmZi * Chris McDonough pointed out that Python's creator Guido van Rossum mentions Zope as in his latest interview. http://www.oreilly.com/frank/ * Andy Dustman released MySQLdb-0.1.1 which provides access to MySQL from Zope. http://www.zope.org/pipermail/zope/1999-October/011978.html * Chris McDonough mentioned that Linux.com has donated space for a Zope ad. Lots of discussion ensued about what the ad should say. http://www.zope.org/pipermail/zope/1999-October/012037.html * The indomitable Chris McDonough produced an interesting comparison between Zope and MS SiteServer. http://sharon.iqgroup.com/zopevssiteserver.html http://www.zope.org/pipermail/zope/1999-October/012115.html * Brad Clements expressed interest in taking over NotMail development. Go Brad! http://www.zope.org/pipermail/zope-dev/1999-October/001771.html As always this summary cannot do justice to all the frenetic Zope activity, but it can perhaps highlight a few interesting items you may have missed. See you next week. -Amos -- Amos Latteier mailto:amos@digicool.com Digital Creations http://www.digicool.com

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RE: [Zope] Need help trying to add objects to a Object Manager ZC lass
by Jay, Dylan 13 Oct '99

13 Oct '99

> -----Original Message----- > From: Stuart 'Zen' Bishop [mailto:zen@cs.rmit.edu.au] > Sent: Wednesday, October 13, 1999 21:09 > To: Jay, Dylan > Cc: zope(a)zope.org > Subject: RE: [Zope] Need help trying to add objects to a > Object Manager > ZC lass > > > On Wed, 13 Oct 1999, Jay, Dylan wrote: > > > > You need to inherit from Folder as well. > > > This one bit me last week. :-| > > > > This doesn't work. Can anyone tell me why this might be > happening????? I'm > > really starting to think ZClasses are just a complete waste of time. > > I think what is happening is the following: > Some objects think of themselves as 'methods'. If you ask them for > this(), they will report their container object. > > Other objects, like folder, report themselves when asked > for this(). > > If you are inheriting from multiple baseclasses, the order will be > significant. Try making folder the first object in the list > you inherit from. If this doesn't work, try making it the last > (I don't know if the top of the list or the bottom will > take precedance). I have yet to try this however isn't there a conflict here between ZCatalogAware. I thought that ZCatalogAware had to be the first to be inherited?

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REVIEW: "How-To: Z Class Properties"
by Loren Stafford 13 Oct '99

13 Oct '99

I've collected some more information on managing properties in Z Classes into a "How-To" at http://www.zope.org/Members/lstaffor/zProperties. Before I have it registered as an official "How-To", please check it out and make sure that it is accurate and helpful. In particular, I've make some blanket statements positioning Z Classes and Properties within the general field of O-O programming. I'm no expert on O-O, so I might be a little off-base. Please help keep me from leading others astray with inaccurate statements. -- Thanks -- Loren

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Infinite recursion in Document Template
by David C. Morrill 13 Oct '99

13 Oct '99

Can someone explain to me why the following causes an "Infinite Recursion in Document Template" error? <dtml-in "PARENTS[0].objectValues(['DTML Document','DTML Method'])"> <dtml-with sequence-item only> </dtml-with> </dtml-in> Dave Morrill

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Global Product Configuration and GUIs
by Johan Carlsson 13 Oct '99

13 Oct '99

Hi, (With products I mean Python products not ZClass products) I have been thinking about how one can use global product configuration properties, to make dynamic products (but on a global level). Using a configuration file in the Products/product directory would be one way to do it. But I really would like to put configuration forms in the Control Panel/Products/product area and/or save configuration properties as objects/object-properties instead of conf. file. Anyone have suggestions how to do this? Regards, //johan torped johan carlsson birkagatan 9 113 36 stockholm telefon 08-32 31 23 mobil 070-558 25 24 fax 08-32 89 47 johanc(a)torped.se

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Re: [Zope] Linux.com community ad
by Tres Seaver 13 Oct '99

13 Oct '99

Zope -- the Zen of the Web -- ================================================================================ Tres Seaver tseaver(a)palladion.com http://www.palladion.com Palladion Software Houston, Texas, USA 713-523-6582

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RE: [Zope] zope vs. siteserver from ms.siteserver newsgroup
by dale w lance 13 Oct '99

13 Oct '99

> -----Original Message----- > From: Brian [mailto:Brian@digicool.com] > Sent: Wednesday, October 13, 1999 11:42 AM > To: chris; zope > Cc: Brian > Subject: RE: [Zope] zope vs. siteserver from ms.siteserver newsgroup > > > > Here's an exchange I had with a guy in the MS Site Server > > general Usenet > > Newsgroup... can anyone find exception with his or my arguments? > > Additionally, he doubts the ability of Zope to handle large > > sites (near the > > end of the message). Any clarifications are appreciated.... > > > > > > On the opposite, ZOPE is interpreted, not only the > > templates, even the > > > server itself. No paradigm like COM is part of the game > > (though it might > > > be extended). So ZOPE will be less speedy. > > COM happens to work just fine with Zope :^) I've written a > demo ExchangeFolder before that let you march into the > Public Folders on your Exchange server as a little test too > see if it would work. To me, the whole argument of "COM > components are compiled, so they'll be faster" is sort of > a lark anyway. > > If you wanted to, you could crank up your copy of VC++ and > crank out a COM component for your business logic. The fact > that people don't seem to be doing this (or even clamoring > for info on how to do this) is telling. From the point > of view of a web developer, the issue is not "gee, how many > milliseconds faster can this COM component execute my query", > its "how fast can we get this project done". Some people seem > inexplicably not to have caught on to that yet :^) > > > > > > > > Also: I really doubt the scalability of the ZOPE Object database, > > > compared to the SQL Server that is part of the site server > > licensing. > > > The ZOPE Object database - well - there are no benchmarks on it. > > There are no benchmarks, true. It might be worth noting, though, > that the actual backing storage of the object db is pluggable, > documented and extensible. This architecture is specifically > designed to allow the use of alternate backing stores (oracle, > other enterprise dbs, etc.) -- including SQL Server if you were > so inclined. > > > > > "When you do this, you're basically extending the Zope > > environment by > > > creating your own object types without having to know a high-level > > > programming language (ala C++/Visual Basic COM object > > development)." - > > > well, just you do it in a slow interpredet language, where C++ COM > > > Objects will be speedy! > > Yep, speedy as hell - and a year late ;^) See above. > > > > > "The power of this model is formidable. For example, I > developed a > > > "news item" object in 22 minutes which allows my users to > add "news > > > items" to their department for perusal by other department > > members." - > > > nive. What about adding 100.000 news items. What is the > performance > > > then? This is unrealistic? OK, lets make an interface for a > > news server. > > > 1 million messages a day. Youre dead. > > This seems a simpleminded argument. If you are going to do > something like a news server interface, you are also going > to do the obvious design work beforehand that takes scale > risks into account. I believe he entirely missed the most > important points of your statement - "22 minutes", the > implied department-level scope of your solution, and the > fact that it worked for you. > > The "youre dead" bit makes me wonder whether it's really worth > much time bothering with this guy - you can't really answer > someone who obviously already knows all the answers :^) > <RANT> I guess he also misses the point that every time the other operating system (read MS) people come out with a new version it requires a much larger, more powerful machine? </RANT> The idea is to make tools that get software to market faster and better. Zope handles COM (see other replies). Zope interfaces to his database. The only thing left is the Zope development paradigm vs his. Of course this argument has gone on since the 60s and 70s. There has been no luck convincing the other side, but here we are with bigger, faster computers to run interpreted languages (among other things like megalithic office productivity suites etc) Dale Lance

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RE: [Zope] Newbie: need a simple example of external method
by Hung Jung Lu 13 Oct '99

13 Oct '99

Wow, thanks everyone. (Loren, too.) This was much faster than wading through the tons of help files. At some point we should make some document with searchable index to help people finding this kind of information faster. Right now the documentation is a little bit all over places and hard to use. .......... I have noticed that the external methods are only single-level deep. That is, they have one-word names, e.g: myMethod. This might be a problem in large-scale projects, where it is easy to run into name conflicts. Does anyone know whether internally zope uses the "import myModule" and then internally assembles the "myModule.myMethod()" call, or does it use "from myModule import myFunction"? I mean, has any zope users used method calls like myObject.myInnerObject.myFurtherInnerObject.myMethod()? I guess it's ok for Zope to use "from ... import ..." instead of "import ...". It's just that I am very afraid of name collisions. regards, Hung Jung -----Original Message----- From: Pavlos Christoforou [mailto:pavlos@gaaros.msrc.sunysb.edu] Sent: Wednesday, October 13, 1999 1:57 PM To: Hung Jung Lu Cc: 'zope(a)zope.org' Subject: Re: [Zope] Newbie: need a simple example of external method Welcome - On Wed, 13 Oct 1999, Hung Jung Lu wrote: > > myprogram.py: > > def myfunc(x): > return 2*x; > > How do I proceed to use it in DTML, and how do I > place it in the external methods folder? First go in your Zope management screen and select external method from the available object list. Add an id (lets say testit) add the function name (in your case myfunc) and then the python module file (which should exist in the Extensions directory in the main python distribution. In your case myprogram.py) click add and that's about it. In a DTML method you can call your function by simply calling: <dtml-var "testit(3)"> should print out 6 Pavlos

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