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RE: [Zope] Database connections
by Paul Everitt 23 Mar '99

23 Mar '99

Oleg writes: > I've finished large project using pure CGI concept (I used Neale's > html.py). Now I (and my boss) are thinking of switching to Zope, or at > least ZTemplates. > > While playing with Zope and SQL (I am using Postgres, hence ZPygres > Database Adapter), I found that Zope, when loaded into memory > by Zope.cgi > (I am using Apache, and need to use in the future) opens a database > connection for every Folder where I created Connection object. Ahh, no need. Just put one Database Connection object in the top folder and all the subfolders will "acquire" it. That is, any SQL Method defined lower down can use it. > It is bad, as I have many databases, so Zope eats up > memory. Another > problem - what would do Zope if I restart Postgres (so all current > connections break)? Would Zope reestablish connections or just report > error? It should re-establish the connection. If it doesn't then there's a bug. This works fine with all the Database Adapters I've used. > How could I limit number of connections Zope opens? How could I There is one connection per Database Connection object. > define a timeout, after which Zope close a connection if there is no Hmm, this is quite a hard thing to do, unfortunately. > activity between Zope and Postgres? and reestablish connection when > application ask for SQL data? > > With ZTemplates and CGI all these questions has one easy > (but not so > nice) answer - there is no constant connection, a connection > established on > every CGI invocation. Of course this means the CPU gets a tremendous beating on every request and the response time goes down. > PS. BTW, I wrote short introduction to Zope in Russian: > http://sun.med.ru/~phd/Russian/Zope/ > Any Russian here to verify my understanding of Zope? Mind if I add a blurb to the Zope News about it? --Paul

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ZSQL direct traveral question
by John Eikenberry 23 Mar '99

23 Mar '99

I've been messing around with using direct traveral on the ZSQL methods. I'm having a problem getting the traveral to work with anything more than one level of depth, eg: http://zope.kavi.com/mem/2/comp_admin/contacts/ Where 'mem' is the ZSQL query (that takes one arg), and the arg is '2'. But it does work in this case: http://zope.kavi.com/comp_admin/contacts/mem/2/ Is this a restriction on the use of ZSQL direct traveral, or am I doing something wrong. If this is a restriction on how you can use direct traversal, I was wondering why, and if it'd be possible to 'fix' this. If so, I'm willing to do it and supply a patch, I assume this is functionality comes from Zope/lib/python/Shared/DC/ZRDB/DA.py, either in the DA.__call__ or in the Traverse object. I'll have to mess around with it a bit to figure out exactely whats going on (but I figured I'd ask about it first). --- John Eikenberry [jae(a)kavi.com - http://taos.kavi.com/~jae/] ______________________________________________________________ "A society that will trade a little liberty for a little order will deserve neither and lose both." --B. Franklin

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RE: [Zope] Zope Database in XML
by Theodore Patrick 23 Mar '99

23 Mar '99

If you can access the database directly through this interface(xml/pickle), couldn't you *potentially* map a network drive to the interface(cifs/nfs). This could allow you to render data in and out of the database through the file system interface rather than ftp/http. Just a thought! Theodore E. Patrick email: tpatrick(a)indigonetworks.com <mailto:tpatrick@indigonetworks.com> phone: 615-777-0070 ext.125 Indigo Networks - The Ultimate Choice In Who Sees You. http://www.indigonetworks.com

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Zope Database in XML
by Jim Fulton 23 Mar '99

23 Mar '99

A side project of mine is to allow conversion to and from Zope databases (and export files) and XML. This will allow people to more easily access their data without Zope and correct problems, such as moved or renamed software modules, that prevent data from being unpicklable. I've completed a first cut at a tool for converting a Zope database to XML format. It is provided in the file 'bbb.py' in a 'utilities' directory that will be included in the distribution directory of the next Zope release. If you want to get this now, you can get it via Zope public CVS access. See http://www.zope.org/Community/Services/CVS_public_access for details. To run the tool, use: python utilities/bbb.py -rxml var/Data.bbb For now, the tool provides a way to "get at" your data without Zope and get a bit more of an idea of how Zope organizes data in the database. The file uses a module 'ppml.py' (Python pickle markup language :) that must by in the same directory as bbb.py or in the Python path. ppml.py provides for conversion from Python pickles to XML. It will eventually provide conversion from XML to Python pickles. Comments from members of the XML SIG (those who happen to spend time here too) would be welcome. I haven't written a formal DTD for this XML format. I would like to use a standard Python XML pickle format, but I'm not sure if such a thing exists yet. I took the approach of conversion to and from Python pickle format for two reasons: - It allows me to do conversion to and from database format without actually creating any (application objects). This is much faster than creating actual objects and does not require that any application Python modules needed to unpickle objects be around or working. For example, this allows conversion of objects that are not unpicklable. - It means that many of the implementation details of pickling can be avoided. Of course, in combination with the Python pickle modules, pickling objects to XML is straightforward: import pickle, ppml print ppml.ToXMLloads(pickle.dumps(myobject)) Enjoy. Jim -- Jim Fulton mailto:jim@digicool.com Python Powered! Technical Director (888) 344-4332 http://www.python.org Digital Creations http://www.digicool.com http://www.zope.org Under US Code Title 47, Sec.227(b)(1)(C), Sec.227(a)(2)(B) This email address may not be added to any commercial mail list with out my permission. Violation of my privacy with advertising or SPAM will result in a suit for a MINIMUM of $500 damages/incident, $1500 for repeats.

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Trying to understand the Scheduler
by Pedro Vale Lima 23 Mar '99

23 Mar '99

Zope is great. It's so great that I guess I'm trying to use it for doing something different from what zope it's expected to do. I want to make some SQL scripts to access different databases and collect the data in a new table. That I can do with the following external method that calls see_data and put_data ZSQLMethods def get_data(self): result = self.see_data() self.put_data(value=result._data[0][1]) return None Then I wish to make this kind of data management automatic every hour. I dug in the sources and I found out the Scheduler class, which I think is what I need (is it?). But I'm having some trouble using it. This was the external method I tried (without success). def eventGetData(self): rev = RegularEvent(get_data,(),interval=60) self.schedule(rev) return(None) It seems that RegularEvent is not available. Besides, is schedule available trough acquisition in the folder? Can someone give me some light on this. I don't even know if it's possible to use the Scheduler with external methods so it would be great at least to know I'm in the right path. Thanks -- Pedro Vale Lima eq3pvl(a)eq.uc.pt

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#tree - trouble
by Sture Lygren 23 Mar '99

23 Mar '99

Hi! How come this code (from within index_html) doesn't show files and folders within my folder?    (  ) doesn't work either) This is using Zope 1.10.2 on linux (2.0.35) All I get is a blank screen - how come??

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Re: [Zope] #tree - trouble
by Martijn Pieters 23 Mar '99

23 Mar '99

At 12:25 23-3-99 , Sture Lygren wrote: >Hi! > >How come this code (from within index_html) doesn't show files and folders >within my folder? > > > > > >(  ) doesn't work either) > >This is using Zope 1.10.2 on linux (2.0.35) > First, you should use branches_expr, instead of branches. And second, it depends on what type of DTML object you have this code in. Is this code in a DTML Method or a DTML Document? If it is a Document, you'll have to specify the Folder you want the tree to start at::    -- Martijn Pieters, Web Developer | Antraciet http://www.antraciet.nl | Tel: +31-35-6254545 Fax: +31-35-6254555 | mailto:mj@antraciet.nl http://www.antraciet.nl/~mj | PGP: http://wwwkeys.nl.pgp.net:11371/pks/lookup?op=get&search=0xA8A32149 ------------------------------------------

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Re: [Zope] one 'document' in many 'folders'
by Stefan Franke 23 Mar '99

23 Mar '99

[Pleased of having caught Jim Fulton in verbose mode 8-] > You can store any complex Python data in the DB subject to: [...] > - Subobjects of persistent objects must be "persistent" or > they must be immutable, or be used immutably, as in: So class Persistent's __setattr__ is basically also the level that transaction and undo support work on? Can I expect the undo support to work if I take care of the persistence rules, regardless of cyclic and acyclic structures? Propably about time to switch to Zope-dev... Stefan

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Re: [Zope] one 'document' in many 'folders'
by Stefan Franke 23 Mar '99

23 Mar '99

Jim Fulton wrote: > Sorry you didn't get an answer. There is no problem with creating > acyclic or cyclic graph constructors in the, uh, object hierarchy, > which BTW, need not be a hierarchy. :) Not too long ago I experimented a little with cyclic structures inside Zope's database. One thing I noticed was, that the copy support failed with tracebacks like this: Traceback (innermost last): File D:\Programme\zope\koelnzope\lib\python\ZPublisher\Publish.py, line 877, in publish_module File D:\Programme\zope\koelnzope\lib\python\ZPublisher\Publish.py, line 590, in publish (Info: /BLS/1000/ADV-Angelegenheiten/manage_pasteObjects) File D:\Programme\zope\koelnzope\lib\python\OFS\CopySupport.py, line 176, in manage_pasteObjects (Object: Navigation) File D:\Programme\zope\koelnzope\lib\python\OFS\CopySupport.py, line 361, in _getCopy (Object: Navigation) File D:\Programme\zope\koelnzope\lib\python\BoboPOS\PickleJar.py, line 327, in export_file File D:\Programme\zope\koelnzope\lib\python\BoboPOS\SimpleDB.py, line 958, in exportoid ExportError: Object 184337 references itself This led me to the conclusion to better leave my hands off non-hierarchic data structures which differ from those created by the management interface itself. >> Would also like to hear more about this... > Like what? :) More or less simple answers like "this is ok and this is not", or "you can store any complex Python data structure inside the DB, but in conjunction with the management interface, you get the following drawbacks.." I'm still a quite unclear about the object management in the database itself and the management layer Zope adds. But maybe I just have to read the docs harder ;-) Stefan >

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Database connections
by Oleg Broytmann 23 Mar '99

23 Mar '99

Hello! I've finished large project using pure CGI concept (I used Neale's html.py). Now I (and my boss) are thinking of switching to Zope, or at least ZTemplates. While playing with Zope and SQL (I am using Postgres, hence ZPygres Database Adapter), I found that Zope, when loaded into memory by Zope.cgi (I am using Apache, and need to use in the future) opens a database connection for every Folder where I created Connection object. It is bad, as I have many databases, so Zope eats up memory. Another problem - what would do Zope if I restart Postgres (so all current connections break)? Would Zope reestablish connections or just report error? How could I limit number of connections Zope opens? How could I define a timeout, after which Zope close a connection if there is no activity between Zope and Postgres? and reestablish connection when application ask for SQL data? With ZTemplates and CGI all these questions has one easy (but not so nice) answer - there is no constant connection, a connection established on every CGI invocation. PS. BTW, I wrote short introduction to Zope in Russian: http://sun.med.ru/~phd/Russian/Zope/ Any Russian here to verify my understanding of Zope? Oleg. ---- Oleg Broytmann National Research Surgery Centre http://sun.med.ru/~phd/ Programmers don't die, they just GOSUB without RETURN.

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