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standard_error_message in ZPT
by Sam Boggess 27 Dec '05

27 Dec '05

Does anyone know if it possible to rewrite the standard_error_message in Page Templates? And if so how do you reference the objects within the error message? <p tal:content="here/error_value">error value</p> doesn't work. Thanks.

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Zope Persistence (was: XML-RPC within ZOPE)
by Jan-Ole Esleben 27 Dec '05

27 Dec '05

Thanks; this is a problem we are well aware of. Our solution is to increase the amount of workers, obviously. However, I'm increasingly getting a feeling that for a rather big range of unlikely situations that are nonetheless to be expected, Zope doesn't work _at all_. In a WebServices setting, situations like the one I described, with one server calling back to another server within a call from that latter server and both not knowing anything about the implementation of the other, it would most certainly be extremely hard to foresee the exact setup of such situations and impossible to exclude them for persistent objects that actually _do_ change state (unlike mine). The solution is to not have state in your objects, and thus lose instantly most of what Zope is. However, as I see it, the problem is that what Zope actually _is_ (i.e. mostly the ZODB) is an unhealthy way of coupling data and implementation (which is _exactly_ why my implementation didn't work immediately). This of course comes from its origins in TTW development where there wouldn't actually have been many user made products. Please tell me if I'm wrong with my assumption above, and why. I'm not trying to be inflamatory, this just has me really worried. Ole 2005/12/15, Dieter Maurer <dieter(a)handshake.de>: > Jan-Ole Esleben wrote at 2005-12-11 19:10 +0100: > >Is it at all impossible to use XML-RPC _within_ a ZOPE architecture? > > In principle yes. > > Be careful however: it is easy to introduce deadlocks! > > When during request processing you call back into the same > Zope via XML-RPC, the calling out request will not complete > until the XML-RPC returns a result (this always holds for > calls, XML-RPC or other, to an external or internal server). > > Zope has a limited amount of workers (the default is 4) able > to execute requests. If there are no free workers, requests > have to wait for one. > > Now imagine that as many requests arrive as there are workers > and each of them wants to perform an XML-RPC against the > same Zope. Then you have a deadlock: none of the XML-RPC requests > will finish, because there are no free workers. An no worker > will ever become free again, because each of them waits for > its XML-RPC to finish. > > Therefore, you should directly call internal resources (rather > than use XML-RPC). > > > -- > Dieter >

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Rakun XML Application Platform version 0.3.1 released
by Evrim Ozcelik 27 Dec '05

27 Dec '05

Hi, Rakun aims to integrate database applications into Plone. Currently, it makes existing databases accessible through Plone and supports business logic via scripts. The long-term goal is to provide an enterprise application development framework complete with detailed authorization, workflows, report generation etc. Rakun uses Formulator for specifying the database properties in Zope. It supports PostgreSQL, MySQL and SQLite. For additional information about the project, please visit the home page http://www.rakun.org/ -- Evrim Özçelik Computer Engineer Rakun Core Developer http://www.rakun.org/ +90 212 285 60 56 - 118

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ZDaemon for wsgi server
by David Pratt 26 Dec '05

26 Dec '05

Hi I am looking at light wsgi servers to serve an app but want it to be started from command line and have the thread spun off so it stays running (instead of tying up a terminal until a interrupt is given). I was thinking that perhaps ZDaemon could do this since perhaps I could also get logging as as well and I would not have to potentially write the threading code. If this is reasonable, can someone give me a basic outline for doing this. I am interested in running the wsgiserver locally. Many thanks. Regards, David

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Zope 3.2.0 beta 2 released!
by Stephan Richter 25 Dec '05

25 Dec '05

The Zope 3 development team is proud to announce Zope 3.2.0 beta 2. Zope 3 is the next major Zope release and has been written from scratch based on the latest software design patterns and the experiences of Zope 2. It is our opinion that Zope 3 is more than ready for production use, which is why we decided to drop the 'X' for experimental from the name. We will also continue to work on making the transition between Zope 2 and Zope 3 as smooth as possible. As a first step, Zope 2.8 includes Zope 3 features in the form of Five. This is a long term effort. We're not there yet. **You can't run Zope 2 applications in Zope 3.** Downloads http://zope.org/Products/Zope3 Installation instructions for both Windows and Un*x/Linux are now available in the top level 'README.txt' file of the distribution. The binary installer is recommended for Windows. Zope 3.2 requires Python 2.4.2 to run. You must also have zlib installed on your system. Most Important Changes Since 3.2b1 New features - Added an option to mkzopeinstance to create instances that use ZServer, rather than Twisted. - Changed the way returning large results is handled. Applications can now simply return files to the publisher. Bug Fixes - Added input buffering to the twisted integration - Fixed the plumbing in ZServer so that attempts to return large output efficiently using iterators can actually succeed. For a complete list of changes see the 'CHANGES.txt' file. Resources - "Zope 3 Development Web Site":http://dev.zope.org/Zope3 - "Zope 3 Dev Mailing List":http://mail.zope.org/mailman/listinfo/zope3-dev - "Zope 3 Users Mailing List":http://mail.zope.org/mailman/listinfo/zope3-users - IRC Channel: #zope3-dev at irc.freenode.net Acknowledgments Thanks goes to everyone that contributed. Enjoy! The Zope 3 Development Team

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Zopezen.org
by Brian Sullivan 24 Dec '05

24 Dec '05

Anybody have any idea what has happened to zopezen.org? >From where I am sitting it has been awol for at least a day.

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Managing Content Access and Multiple Users
by Francisco Chamorro 23 Dec '05

23 Dec '05

Hi everyone, I have a process question and wanted to know what tools are available in zope to help me solve this issue. A total of 6 developers/producers access zope on a daily basis and make updates to pages, sometimes the same pages. The problem I'm having is that sometimes one developer will make changes to a page, push those changes to our preview environment for client review and wait for client feedback. Then another developer will access the same page, make his own changes (not realizing there are changes not approved) and push his changes and the non-approved ones to live, causing products to go live before they are supposed to etc. What tools (if any) are available to help me solve this issue? My first thought was to install CVS, but I'm not entirely sure that will solve it entirely. Are there any tools available for work flow in zope? Any help would be really appreciate. Thank you. -Francisco

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More on understanding conflicts
by Dennis Allison 23 Dec '05

23 Dec '05

Zope 2.8.4 ZODB 3.4.2 I have a dtml method which is an obvious hotspot. It puts up navigation wigetry and is rendered on nearly every page. The logs show it generates a large number of conflicts. The conflicts are in TemporaryStrorage and so are due to session variables. The session variables are accessed with short Script(Python) functions one call per session variable used: getSessionVariable( var ), Session variable hold mostly data that is constant throughout the session. There are about twenty values, ten of which are referenced in the navigation method. The structure of the method is simple enough: there is a large <dtml-let> block which populates local variables with data from the session variables <dtml-let foobar="getSessionVariable('foobar')" ... > with the body of the <dtml-let> containing 300 lines or so of dtml, control code, sql queries, and occasional dtml-let blocks to hold query results and computed values. So, this navigation method is clearly a good candidate for refactoring, but the question is "What's the best way to refactor it?". I still don't have an intuitve understanding of the conflict mechanism in practice. For example, Why is the conflict error reported for the navigation dtml method rather than for the getSessionVariable python script which actually references the SESSION object where the conflict occurs? A conflict error gets raised whenever another thread references the same session's SESSION object. Apparently the MVCC read-read conflict resolution fails for session variables although I am not sure why. The DEBUG logs indicate that read-read conflicts found. It would be helpful to understand why. When the conflict is resolved, one is backed out (everything is transactional) and restarted. After three retries, it is considered an error. This processing is handled automatically by Zope. At one point, I had considered writing a custom conflict resolution function where resolution assumed independence of individual session variables. After some thought and experimentation, I concluded that was a bad idea because it could break synchronization assertions between session variables (e.g., X is twice Y). Absent a magical conflict resolution method, the best approach would seem to be to minimize the potential for conflicts. Intuition says that the simplest way to do this would be to have the navigation dtml method make a single call to a python script, getSessionVariables, which would return a copy of the session variables. The copy could then be unpacked and processed without any potential conflict errors.

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FTP rights problem
by Martin Koekenberg 23 Dec '05

23 Dec '05

Hello, When a user connects with FTP to a Zope folder with only rights on that subfolder he can't create a folder or delete files. He has the Manager role and all the rights. Is this a bug or do I have to give this user Manager rights to the root of the zope instance ? Or is there an other solution to get the FTP working ? Regards, Martin Koekenberg

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List within a list - how to use in a page template
by Cameron Beattie 23 Dec '05

23 Dec '05

I am trying to get my head around representing a list in a page template. Assume the following list: >>>m [[61282125371L, 1, 6, 0], [61282125379L, 1, 6, 0], [61282825240L, 6, 6, 0], [61282125378L, 1, 6, 0], [61282125374L, 1, 6, 0] >>>m[0] [61282125371L, 1, 6, 0] >>> m[0][0] 61282125371L i.e. m is a list where each member is itself a list. How do I get a page template to render a particular item? Assume a function getem returns the list. <tal:block repeat="m python:here.getem()"> <td tal:repeat="single m" tal:content="single"></td> This code will produce four columns and five rows, with each populated by the list members. But what if I only want the first and third members in each case i.e. 2 columns and five rows? I thought it would be something like tal:content="python:single[0]" but that gives me an unsubscriptable object error. Any suggestions would be appreciated. Cameron

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