Re: [ZODB-Dev] ZEO for GUI applications
Robert Gravina wrote at 2007-4-1 00:31 +0900: ... Woohoo! I realised Connection.sync() does exactly what I need, but this still doesn't work as expected. class UpdatedDB(DB): def invalidate(self, tid, oids, connection=None, version=''): DB.invalidate(self, tid, oids, connection, version) if connection is not None: connection.sync() Am I going about this the right way? Recently, Chris Withers reported a strange AssertionError after a call of loadBefore. The following discussion lead to the conclusion that the current ZODB code (its MVCC part) may not allow to call invalidate when the objects was not modified. If, on the other hand, the object was modified, invalidate is called automatically. No need to do it yourself. Furthermore, be aware that Connection.sync aborts the current transaction. -- Dieter ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] ZEO for GUI applications
On Mar 31, 2007, at 10:32 PM, Stephan Richter wrote: On Thursday 29 March 2007 15:14, Robert Gravina wrote: Is anyone using ZEO to build mutliuser networked applications outside of Zope? Uwe Oestermeier and his team built Bebop. While the server component uses Zope 3, it uses a full wxPython GUI as client. http://svn.kmrc.de/ Wow, that looks very impressive. I'll checkout the source and have a look around to see what I can learn. Thanks, Robert ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] ZEO for GUI applications
On Mar 31, 2007, at 11:13 PM, Robert Gravina wrote: On Mar 31, 2007, at 10:32 PM, Stephan Richter wrote: On Thursday 29 March 2007 15:14, Robert Gravina wrote: Is anyone using ZEO to build mutliuser networked applications outside of Zope? Uwe Oestermeier and his team built Bebop. While the server component uses Zope 3, it uses a full wxPython GUI as client. http://svn.kmrc.de/ Wow, that looks very impressive. I'll checkout the source and have a look around to see what I can learn. Thanks, Robert I'm still a little bit unsure about how to update the GUI when objects are changed. I noticed a previous thread on a similar topic which suggested to customise ZODB.DB.invalidate. http://www.mail-archive.com/zodb-dev@zope.org/msg01969.html I thought I could check the type of object, and generally that will be enough for me to decide which parts of the UI need a refresh. It seems though, that when I change data from one client other clients, although getting invalidate messages, are still displaying old data. I tried subclassing DB, and printing out the object as a test, but it's always None (even when I have a few clients connected). The code there to get the object from the cache I don't quite understand, I just copied it from ZODB.DB.invalidate and hoped for the best :) class UpdatedDB(DB): def invalidate(self, tid, oids, connection=None, version=''): DB.invalidate(self, tid, oids, connection, version) for oid in oids.keys(): h = hash(oid) % 131 o = self._miv_cache.get(h, None) print o Is there anything else I need to do/doing wrong? Robert ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] ZEO for GUI applications
On Mar 31, 2007, at 11:41 PM, Robert Gravina wrote: On Mar 31, 2007, at 11:13 PM, Robert Gravina wrote: On Mar 31, 2007, at 10:32 PM, Stephan Richter wrote: On Thursday 29 March 2007 15:14, Robert Gravina wrote: Is anyone using ZEO to build mutliuser networked applications outside of Zope? Uwe Oestermeier and his team built Bebop. While the server component uses Zope 3, it uses a full wxPython GUI as client. http://svn.kmrc.de/ Wow, that looks very impressive. I'll checkout the source and have a look around to see what I can learn. Thanks, Robert I'm still a little bit unsure about how to update the GUI when objects are changed. I noticed a previous thread on a similar topic which suggested to customise ZODB.DB.invalidate. http://www.mail-archive.com/zodb-dev@zope.org/msg01969.html I thought I could check the type of object, and generally that will be enough for me to decide which parts of the UI need a refresh. It seems though, that when I change data from one client other clients, although getting invalidate messages, are still displaying old data. I tried subclassing DB, and printing out the object as a test, but it's always None (even when I have a few clients connected). The code there to get the object from the cache I don't quite understand, I just copied it from ZODB.DB.invalidate and hoped for the best :) class UpdatedDB(DB): def invalidate(self, tid, oids, connection=None, version=''): DB.invalidate(self, tid, oids, connection, version) for oid in oids.keys(): h = hash(oid) % 131 o = self._miv_cache.get(h, None) print o Is there anything else I need to do/doing wrong? Woohoo! I realised Connection.sync() does exactly what I need, but this still doesn't work as expected. class UpdatedDB(DB): def invalidate(self, tid, oids, connection=None, version=''): DB.invalidate(self, tid, oids, connection, version) if connection is not None: connection.sync() Am I going about this the right way? Thanks, Robert Robert ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] ZEO for GUI applications
On Mar 30, 2007, at 5:55 AM, Robert Gravina wrote: On Mar 30, 2007, at 5:24 AM, Rodrigo Senra wrote: That is precisely what I did in the first example I have mentioned, and it worked just fine. Just responding to this thread again to ask if anyone has used ZEO as the basis for a networked app on a larger scale that Rodrigo's test? What I'd like to know is how I will go if I have several (lets say, 100 max) GUI clients connected to one ZEO, assuming the application has relatively few writes. I'd just like to know if anyone else out there is using ZEO in this way, or if developers think this is a bad idea. Programming-wise, I couldn't be happier. It is simply amazing to be able to share a object database over a network like this (to my little brain anyway). Robert ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] ZEO for GUI applications
On Mar 30, 2007, at 5:24 AM, Rodrigo Senra wrote: [ Robert Gravina ]: |short version: | |Is anyone using ZEO to build mutliuser networked applications outside |of Zope? Well, I have developed a trivial in-house desktop-based employee activity control (Argh!) a couple of years ago. It started as a ZODB+wxPython standalone exercise, and changing one line the application (from FileStorage to ClientStorage) ;o) ... and adding ZEO ... it became a client/server desktop apps. It always amazes me that in ZEO you can do that. When I'm coding apps for users to manage some kind of shared data, that's the kind of level I like programming at. Why is it with other frameworks I have to jump through hoops to do something which, to me, seems like every multi-user networked application is going to need? It impressed some folks down here and it was in production use until it was finally replaced for a Web version integrated to our Zope/Plone portal. Yeah everyone wants to go web these days. I don't understand how users put up with web pages trying to be GUI forms when they could just have a proper GUI :) Anyway I'm getting off topic... Having said that, I believe that is not the list to discuss it. :o) |longer version: | |I've been designing and coding (and re-designing and re-coding) a |multi-user GUI application in Python for some time now. At this |stage, it's mainily just GUI forms for editing data and some logic to |share objects with users, keep them from editing the same entry at |the same time etc. I'm currently using Twisted and a a python object- |reational DB called Axiom, built on top of sqllite. I did a curious experiment during a cross-language event that took place in Sao Paulo/Brazil. Several guys presented their favorite programming languages and frameworks: Java-something, Rails, PHP- something and Python (me). While the Java presentation was taking place, I have coded (on the fly) the same example presented there. As an introduction to my talk (last in the day) I presented to the audience my crude ZODB+Twisted version, that had the strengths of all frameworks and yet was much smaller and coded by a mediocre developer while distracted by a Java-something talk ;o) :) I actually was using ZODB+Twisted before I used Axiom+Twisted, but without ZEO it really doesn't matter what DB I use. It's a shame to have wasted all this time I've spent on the Twisted version, when really I should have written a small ZEO test application to see if my ideas would work out. I think this weekend I will do just that, and think about if I should spend the time porting my app to ZEO. There are so many ways I can think of this cutting down on the code I write - e.g. GUI forms for editing the main types of objects in the app could start a transaction when they are created, allow the user to modify the attributes as they see fit, and commit when Save is clicked, or rollback if there was a validation error. Currently there is so much code in my app for a simple update like this - first I make deep copies of objects so users don't edit the original versions, then if it validates OK I send to the server where it copies attributes accross and updates lists etc. etc. then notifies clients that the object has changed. It's not that I am lazy, I just don't trust the code I write to do all this and keep clients in sync, even with tests. It's a hard problem to solve. The full history is here [1], even though in Portuguese, the Python code is Universally readable. [1] http://article.gmane.org/gmane.comp.python.brasil/21504/ match=senra+zodb+twisted+tempo+real thanks That is precisely what I did in the first example I have mentioned, and it worked just fine. But I had a very controlled environment (our tiny little company) and very savy user base (all Python developers). If your application have many more reads than writes you will be fine. In case you want to discuss this in PVT, feel free to email me. Yes, my application definitely will have more reads than writes. i think I'll spend some time trying to get the current incarnation of the app going with ZEO over the weekend and see how I go. Robert Abração, Senra - Rodrigo Senra GPr Sistemas http://www.gpr.com.br ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
