September 2000 - Zope

are there any known memory leaks in Zope 2.2.1?
by Skip Montanaro 12 Sep '00

12 Sep '00

I'm experiencing bad memory leaks in my ZServer-based system. I recently upgraded from 2.0.0 to 2.2.1. I didn't have leakage using 2.0.0 - certainly nothing like I'm seeing it now. When I call the same method (same parameters as well) over and over, I pretty significant leakage via isolate methods exposed through ZServer to test scripts that don't use ZServer, no leakage occurs, so I'm beginning to think there's something amiss with ZServer or DocumentTemplate (the two pieces I use most heavily) or the parts they use. Unfortunately, even disconnected from ZServer, my code is still pretty dependent on my own environment so I can't easily post a script for people to gaze at. One simple method (just executes a DocumentTemplate and returns the resulting HTML) seems to be growing at a rate of about 16kbytes every five to ten times it's called. A search method that calls an XML-RPC server to do the work is much worse, growing at a rate of 85kbytes to 100kbytes per call. It's certainly possible that I'm creating some garbage that Python's reference counting can't reclaim, but when I run my server under Python 2.0b1 with the new garbage collector enabled (and collecting at each call) it never finds anything to collect, so it would appear that the garbage is either being created at a lower level (non-Python heap allocations in C code) or Python objects are getting appended to lists or dicts that are visible to some part of the system (just not obvious to me). What tools are available to try and detect memory leaks in Zope-ish applications? What input can I provide to DC or other interested experts to help track this down? Thx, -- Skip Montanaro (skip(a)mojam.com) http://www.mojam.com/ http://www.musi-cal.com/

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Defining a session idle timeout value using FSSession...
by Aaron Bostick 12 Sep '00

12 Sep '00

Would anyone on the list have a solution to implementing idle timeouts using FSSession? I know you can cron up a simple job to delete the FSSession hierarchy based on date and time, but how do you know which sessions are still being used if you want to delete stuff say every 10 minutes or so? I logged on this morning to find out my session was still active from last night! Oh boy! Thanks folks! Aaron Bostick

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Re: [Zope] Re: Session support (was: Object serialization between different pages)
by Chris McDonough 12 Sep '00

12 Sep '00

Hi Tom, > I just read your proposal and I think it would be nice to have such a > standard product in Zope. Certianly since lot's of these 'shopping carts' > websites are popping up on the internet. > I've however one question, which is more generally to e-commerce products > and which perhaps give this product this little extra then others. At the > moment all? these e-commerce products need 'cookies'. To which ecommerce products are you referring? > This implies that the > user needs to have this feature enabled. People who don't want cookies or > just don't know how to set it, will not be able to 'shop'. > Now, isn't there a possible solution for? Yes, url-rewriting. I even saw one product that went as far as too hook into DNS to dynamically create "fake" hosts on-the-fly to use as a session key. > Perhaps not that good as cookies, > but it can be a solution. I believe cookies are placed on the client > computer and that they can stay alive or be removed after a certain time. > So, isn't it possible to mimic these cookies on the server site (while the > session is active)? Mimic, no... not permanently, unless a rewritten URL is bookmarked. The server needs some indication on a request as to what session the client belongs to. Cookies provide this more or less transparently, while URL-rewriting is slightly more intrusive. > The only problem I see is that we need to be sure to > connect the correct server-file with the correct user. But isn't this > possible with information out of the HTTP request? Yes, a cookie or a URL (or POST variables) with a session key embedded somewhere. > This way we create a > file on the server (with a name which uniquely identifies the client) or > zope-object (but this gives the problem that the Zope database will rapidly > grow) A session manager which directly writes files onto the filesystem isn't a scalable solution (sessions cannot be shared across ZEO clients). This is why a nonundoable storage is a related deliverable in this proposal, as it can be shared from ZEO and mounted by several ZEO clients. > when the user starts shopping. When shopping is finished the file is > removed (and eg some information is send to another place sop that people > know something is ordered). The session manager itself checks if certain > session are abandoned and if one is not active (for 20 minutes) it deletes > the file). Yep, there are a few different kinds of garbage collection schemes we can use, this is one. > The contents of the file are the same as what you would place in > cookies. A cookie will almost always hold a session id, and maybe other metadata, but probably never any data used directly by the app. The app will go through the session manager, and won't need to know anything about the contents of the cookie. > If the product would have the possibility to have something like this extra > (ie. you can manually choose to have a client or server cookie (or you let > the product decide it automatically ie cookies on -> client cookie > otherwise server cookie)) this would be a nice thing for Zope againts is > competitors. There is no such thing as a server cookie, but a similar failover-to-URL-rewriting scheme can be made available to developers.

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Re: [Zope] Looking for Zope vs. Others at-a-glance comparison
by Richard Moon 12 Sep '00

12 Sep '00

I've enjoyed the contributions on this thread. Some time back I mentioned that what hooked me on Zope was the Relational Database access "out of the box". I liked the way Zope generated a simple database query form and result - so I agree strongly that Zope could hook more people if it did even more useful things without coding. I even suggested others submitted their favourite ideas for a "Wizards of Zope" beauty contest. I've been supplying solutions to clients for xx years now and my philosophy has always been to code at the highest possible level. Don't code in machine code if you can code in assembler, don't code in assembler if you can code in C, don't code in C if you can code in a 4GL, don't code at all if you don't have to :-) Zope offers the potential to be the perfect development environment with tons of really good solutions off the shelf - these can be customised if they have to, we can drop down to Python if we really need to. Perfect. Unfortunately its been difficult to get discussions like this going on zope.org as its mainly devoted to coding problems, while zope-dev is to do with deep and complex zopezen. I know usability is high on Paul Everitts list, 'cos he said so in Paris. Perhaps we need zope-usability.org as a forum for non-technical discussions about Zope development ?

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RE: [Zope] Important Security Concerns
by Coleman, Bryan 12 Sep '00

12 Sep '00

That would cause another whole set of problems, unless apache is inherity more secure than Medusa. I was really wondering what the risks are associated with those two options. - Bryan Patrick Coleman Questcon Technologies (336)273-2428 ext-416 bcoleman(a)questcon.com > -----Original Message----- > From: Phil Harris [SMTP:phil.harris@zope.co.uk] > Sent: Tuesday, September 12, 2000 5:15 AM > To: Coleman, Bryan; zope(a)zope.org > Subject: Re: [Zope] Important Security Concerns > > Another option might be to proxy the Zope server through Apache on port > 80. > > > ----- Original Message ----- > From: "Coleman, Bryan" <bcoleman(a)questcon.com> > To: <zope(a)zope.org> > Sent: Tuesday, September 12, 2000 12:43 PM > Subject: [Zope] Important Security Concerns > > > > I almost have my company convinced that Zope is the technology to use > for > > our Intranet/Extranet. However they are very concerned with security. I > have > > proposed two security schemes that I would like zope community feed back > on > > for potential holes. > > > > Option A: Poke a hole through our firewall on the primary http port or > on > > port 8080 to allow Zope pages through and then require authentication on > the > > first page. > > > > Option B: Set up a DMZ off the firewall to allow the same as the above. > > > > Any feed back would be welcome. > > > > - Bryan Patrick Coleman > > Questcon Technologies > > (336)273-2428 ext-416 > > bcoleman(a)questcon.com > > > > > > _______________________________________________ > > Zope maillist - Zope(a)zope.org > > http://lists.zope.org/mailman/listinfo/zope > > ** No cross posts or HTML encoding! ** > > (Related lists - > > http://lists.zope.org/mailman/listinfo/zope-announce > > http://lists.zope.org/mailman/listinfo/zope-dev )

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Important Security Concerns
by Coleman, Bryan 12 Sep '00

12 Sep '00

I almost have my company convinced that Zope is the technology to use for our Intranet/Extranet. However they are very concerned with security. I have proposed two security schemes that I would like zope community feed back on for potential holes. Option A: Poke a hole through our firewall on the primary http port or on port 8080 to allow Zope pages through and then require authentication on the first page. Option B: Set up a DMZ off the firewall to allow the same as the above. Any feed back would be welcome. - Bryan Patrick Coleman Questcon Technologies (336)273-2428 ext-416 bcoleman(a)questcon.com

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ZSQL and database locking
by Arjan de Knegt 12 Sep '00

12 Sep '00

Dear all, I'm a happy Zope user (in a private environment), experienced in client-server application development but still quite green regarding to Zope. I'm trying to figure out how I can use database locking using ZSQL and MySQL. What is the case? I would like to implement a multi-user update function avoiding the obvious concurrency pitfalls. I usually implement this as follows: 1. Add a "counter" column to every table 2. With every record update, raise the counter for that record with 1 3. Before an update, first read the actual value of the counter in the database. Compare the counter in the database with the counter value of the record currently being edited. 4. If the values are not the same, another user has obviously edited the database in the meantime. The changes will not be updated to the database but the current database record will be redisplayed on the screen (with a message to the user of course). 5. If values are the same, update the database. To avoid concurrency problems, the table has to be locked before step 3 and unlocked after step 5. Because a ZSQL database connection is a permanent connection, the database will see it as 1 single session. All (anonymous) user of the web-update form will use the same session and database locking will have no effect. Now finally my question: Does anyone see a (simple) solution for this? Okay, I could create a seperate MSQL database connection for every user, but that doesn't look very Zope-ish to me. Didn't find a comparable issue in the Zope Mailing lists. Thnx in advance, Arjan.

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Object serialization between different pages
by Pierre-Julien Grizel 12 Sep '00

12 Sep '00

Hi, Is it possible to serialize an object to share it across several pages ? This would allow one to pass the serialized object via the URL, and to retreive it in the form that would process the request. I know there is the pickle function in python, but is there a more Zopish way to do this ? Thanks, P.-J.

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[zwiki] What is the 'Wiki-Safetybelt'?
by Jean Jordaan 12 Sep '00

12 Sep '00

Hi all If I ftp a bunch of zwikipages out of the ZODB, each one has this:: Wiki-Safetybelt: 968246577.617 What is is, and do I need to keep it if I want to ftp them back in? The thing is, I 'diff'ed and 'patch'ed two wikis against each other, and I'm not interested in changes that involve only the the Wiki-Safetybelt. I'd appreciate it if you Cc: me on answers .. I'm on digest mode (and waaay behind on reading those!) -- Jean Jordaan -- technical writer -- Mosaic Software -- Zope 2.1.6 on WinNT and W2K

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TEXT FILE Operation
by Marcello Lupo 12 Sep '00

12 Sep '00

Hi to all, anyone know how to let Zope interact with text files on the system on it is running. Like making changes to files, search and replare some text or insert or delete text and save the file again? I'm pretty new and i don't know if it is possible for Zope. Thank You in advice. Marcello

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