- Zope-Dev - Zope lists

WebDAV API
by Dethe Elza 02 Nov '01

02 Nov '01

Hi folks, Because many existing Windows programs understand FTP but not WebDAV, we're trying to create an alternative way to lock/unlock files when we FTP them. This could be a simple HTTP call (preferred) or XML-RPC. The documentation I've been able to dig up on Zope's DAV implementation isn't too clear on how to programmatically lock/unlock files. I can easily check if a file is locked using DTML Methods, but actually locking it has eluded me. Do I have to create a Lock object first? At first wl_lockItems, wl_lockTokens, and wl_getLock all looked like methods to create a lock, but they seem to be methods for retrieving existing locks, wl_setLock seems to be what I want but I don't see how to create a token or a lock item. Can I do this in a DTML Method? TIA --Dethe -- Dethe Elza (delza(a)burningtiger.com) Chief Mad Scientist Burning Tiger Technologies (http://burningtiger.com) Living Code Weblog (http://livingcode.ca)

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Multi-threaded pcgi vs single-threaded pcgi
by Remi Delon 31 Oct '01

31 Oct '01

Hi, I have a zope backend running behind an Apache server. Up to now, I've been using the "standard" pcgi configuration. Here is my understanding of what's happening (correct me if I'm wrong): - When Apache gets a request, it calls pcgi-wrapper. If the pcgi_publisher process is running, pcgi-wrapper connects to it and gets the page. If pcgi_publisher is not running, pcgi-wrapper first starts pcgi_publisher and then connects to it and gets the page. Now, the problem I have with that is that pcgi_publisher is single-threaded. I have to run long-running background tasks at night to update my database, and I run them inside Zope. During that time, the site is unavailable because Zope is busy executing what should be a background task. The solution I want to use is to start Zope in multi-threaded pcgi mode, using the standard "Zope/start" script with the correct flags (-p) This works fine, as long as I manually execute the start script. But if Zope ever crashes, I would like Apache (maybe through pcgi-wrapper) to automatically restart Zope in multi-threaded pcgi mode, when someone requests a page. How can I achieve that ? Thanks. Rémi. _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp

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Any interest in a set of Zope products to support CVS-versioned, XML/XSLT-based Zope development?
by Craeg K. Strong 31 Oct '01

31 Oct '01

Greetings! We at Ariel have recently started using Zope and, needless to say, we are enjoying a large increase in productivity compared to our previous Apache-Cocoon2-Tomcat-Servlet-dbXML-Java environment. In our opinion, Zope is about a year or two ahead of where these guys are in many respects. Kudos! The main problems we faced while moving to Zope were these: - how to support version control, branching, merging, tagging, etc. etc. (we use CVS) - how to support our XML/XSLT-pipeline based document publishing paradigm (cf Cocoon2) We have seen several efforts underway to address these issues within the Zope community. We have gone a slightly different direction, but hope to contribute to these efforts in some way. In our environment: - multiple author/developers work on the same documents at the same time - we work on content for several clients at the same time - web pages are cobbled together from content pulled from several XML documents, according to a PagePolicy (similar to the way articles are collected and pasted into a newspaper page). - the PagePolicies can be changed independent of the underlying content (header-body-leftmargin-footer, header-body, etc) - all content is in XML, transformed into HTML/DTML by XSLT. - we use lots of tools other than Zope, so we want to keep our content in XML, not pickled Zope objects. (hold the pickles ;-) In order to make all this work, we created three Zope Products: ExternalFile: Points to a file in the filesystem. Unlike ExtFile, it is not copied into a repository directory, but remains "in situ" Behaves similarly to a symbolic link in UNIX or windows shortcut. Metadata stays in Zope, but content stays in the file. index_html and __call__ return the content as if it were a real Zope object, so Zope doesn't know the difference. :-) Due to permissioning and other possible problems, this is probably only appropriate for development, not production. In future, we hope to add an option to copy in the content to ZODB, essentially converting it to a DTMLDocument. At that point we will probably rename the class "ExternalizableFile" more on this later..... CVSFile: inherits from ExternalFile. Same thing, but the file is assumed to be inside of a CVS sandbox. Includes buttons for doing normal cvs commands. Sandboxdir is stored in a cookie, so each developer can access his own sandbox via THE SAME ZOPE OBJECT. That is, all developers can share a single Zope server but each see content from his own sandbox. (play in your own sandbox :-) This avoids the locking issues and other problems inherent in things like CVSwebClient. It also enables the content to stay "native" rather than becoming a Zope extract like in ZCVSMixin/ZCVSFolder. XMLDocument: (Sorry for the name clash). Inherits from CVSFile. Has a notion of a "transformer" property that points to an XSLT transformer. This enables it to be rendered automatically into HTML when __call__ or index_html is called. The underlying XML file can either be external or not. The XMLDocument object represents the entire file, as opposed to the parsedXML stuff that explodes a single document into multiple Zope objects for each XML node (correct me if I am wrong...) There is lots more to do, but we do have initial development versions of all three working in the lab. Is there interest in this kind of Product? Would it be considered heretical? ;-) Are others working on the same thing? Thanks! --Craeg

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Suggestion: Blocking out Localroles?
by Lennart Regebro 31 Oct '01

31 Oct '01

I was going to put this up as a proposal, but I can't figure out how to add a new proposal... :-) Then I checked out the new collector, and there is a possibility to add a "feature" there too, so maybe this fits better there? Anyway, heres the suggestion: When developing a CM system in Zope a customer asked for a possibility to "block out" a persons local role lower down in the hierarchy. That way a person that has manager rights on a country-level could have these rights removed on a regional level. So, we implemented this as a HotFix, that seems to work fine. It also has a user interface for local roles that is somewhat easier (in my opinion) to use. So what do you think? Is this stupid or good? Is it a "feature" or a "proposal"? I attached the files, you can put the __init__.py in any directory under Products, and the dtml-files in a directory 'dtml' under that if you want to try it out. I think it should work with a clean Zope installation (although we haven't tested that for a couple of weeks).

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Twisted, medusa, ZServer, and VFS's
by Donovan Baarda 31 Oct '01

31 Oct '01

G'day, I've just been looking at Twisted Python for the past hour or two, read the mailing list archives, and have some comments and questions. I've been working on using Medusa for serving a virtual mirror via http and ftp. I'm at the point where I'm close, but I'm starting to re-think some stuff, in particular my choice of Medusa. First my impressions of the three contenders; Twisted, Medusa, ZServer. Please correct me if I'm wrong in the following summaries; Medusa seems to be the daddy of them all. It's the oldest, which has benefits and problems. It is a little messy from its evolution, but seems pretty mature. It uses an async select loop to drive everything. It uses "asynchat" derived class objects to communicate on sockets. Data can be sent by pushing "producers" onto asynchat objects. Producers can be complex objects that produce data, execute callbacks, whatever. It's ftp and http server classes use a primative VFS to serve from. The asyncore and asynchat modules it is built on are now part of Python. Twisted seems to be a from-the-ground up re-invention of Medusa. It's newer, but surprisingly it's bigger, dispite it's apparently less mature feature set. It is similar in structure to Medusa, but simplifys it by dispensing with producers. It can use a variety of event-loops, including Tk and GTK, or it's own. It doesen't have a VFS (yet) so its ftp and http servers serve from the underlying os filesystem. ZServer grew out of Medusa. It uses the same basic underlying architecture, but throws in threads to get around the problem of delayed producers blocking the event loop. I'm not sure how tightly tied to Zope it is, but its http and ftp servers generally serve from a ZODB database, presumably wrapped in a Medusa VFS, though I have a feeling they might have changed that. ZServer also supports webDAV serving. It is possible that some of the enhancements could be merged back into Medusa, but probably it has changed so much it would be difficult. My problem with Medusa is its http and ftp servers assume that the VFS can deliver files wrapped in producers without blocking. I've fixed this by creating a patch for Medusa's asynchat that adds support for a ready() method to producers, so they can block without blocking the event loop. I'm currently in the process of writing Medusa VFS's for ftp and eventualy http backends. In the process I've also found that the Medusa ftp server is not as full featured as I want. In my search for Python VFS's I found PyVFS (http://www.pycage.de/) This is modelled on the Gnome/MC VFS, so it supports '/dir/somefile.tar.gz#tgz:/somepath' style paths to look inside tar, tgz, ftp, whatever. The various different VFS backends are loaded dynamicly as pluggins. These pluggins execute as a seperate process that are communicated with over a channel. The API is too simplistic for me, with files being "projected" out of the VFS to a local file to be manipulated/used. I don't like the pluggin-process-channel architecture either. In the reading of the Twisted mailing list, I saw a comment to the affect that the Medusa VFS was an example of how _not_ to do it, which lead to using webDAV as the API for a VFS. My gut feeling is DAV is a cool protocol for a VFS backend, but I dunno about using it as the primary API. Sure, it supports meta- data etc, but the reality is the API that is most widely used and understood is the POSIX filesytem API, as exposed in Python by the os and os.path modules. My solution for a VFS has been, upto now, based on Medusa's, but extending it to be more like os and os.path. So far it's a filesystem class with most of the os and os.path methods. One of the derived classes is a mountable_filesystem that allows you to mount other VFS filesystems off it. At this point I'm tempted to make a vfs module that emulates os and os.path so that you can mount whatever vfs's you want first, and then just replace all your os.* calls with vfs.* calls. Note that the one catch would be open() would need to be replaced with vfs.open(). I'm sort of fishing for general suggestions, comments, and interest. I'm at the point where I've just convinced myself my vfs is worth finishing, and my ready () patch to asynchat is worth updating, but I'm not sure what to use as the http and ftp server front-end, though I'm still leaning towards medusa. It looks like Twister is not ready, and ZServer would be too hard to seperate from Zope. PS... I'm not on the zope-dev list but I am on the twister and medusa lists. The zope-dev list is too much non-ZServer stuff and that's all I'm interested in. So zope-dev'ers, please reply to me or one/both of the other lists directly. -- ABO: finger abo(a)minkirri.apana.org.au for more information.

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Re: [Zope-dev] Any interest in a set of Zope products to support CVS-versioned, XML/XSLT-based Zope development?
by Anthony Baxter 31 Oct '01

31 Oct '01

You might want to look at the fishbowl project on this that was recently announced: http://dev.zope.org/Projects/Wikis/DevSite/Projects/ZopeVersionControl/ (URL copied from Brian Lloyd's earlier email - with a 7s delay in the AU-US net link at the moment, I can't check it's correct, unfortunately...) Anthony -- Anthony Baxter <anthony(a)interlink.com.au> It's never too late to have a happy childhood.

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improving str(REQUEST)
by seb bacon 31 Oct '01

31 Oct '01

The REQUEST __str__ representation can be useful for tracking down bugs, and is a useful didactic tool for newbies. I wanted to get feedback on some ways it has occured to me that it might be improved. If it turns out to be a good idea, I'll do a fishbowl proposal (one day...) In its simplest form, it would be nice if it were a collapsable tree, so you could examine just the bits you were interested in. I think it would also be really handy to extend this concept, for example adding nodes to the AUTHENTICATED_USER branch, which show local roles, roles, etc. Perhaps automatically, through introspection? seb

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Re: [Parsed-XML-Dev] Re: [Zope-dev] ParsedXML in Zclass methods loses permissions on Zope restart
by Karl Anderson 30 Oct '01

30 Oct '01

Martijn Faassen <faassen(a)vet.uu.nl> writes: > Brad Clements wrote: > > I'm still casting around for a suggestion on where I can go to fix this. > > > > I have a ParsedXML object in the methods list of a ZClass Product. > > > > The "Access Contents Information" Permission Mapping always get's reset to "blank" in > > the ParsedXML object when Zope restarts. > > > > Is this a problem with ZClasses, or with ParsedXML? > > Taking a look at ParsedXML, it looks like it just does a very simple > permission definition, so it doesn't *look* like there's something > wrong there. > > What it sounds like is that something that should be persistent isn't > for some reason. Either an object attribute is changed without > the permission mechanism being informed of the change, or it's > for some reason an attribute on a nonpersistent is changed. This at least > would explain why the permission mapping magically goes away.. I don't understand the situation very well, but Martijn's explanation sounds familiar. Remember, there's only one persistent Zope object in a ParsedXML instance, and that's the document proxy object. All of the proxy subobjects are transient, and that includes proxy documents that are navigated to from proxy subobjects. I.E. if "app.foo.PXML" is the ParsedXML instance, then setting Zope attributes on "app.foo.PXML.firstChild()" and "app.foo.PXML.firstChild.parentNode()" won't persist. Same goes if you traverse to these nodes via the web-exposed URLs of these methods. Perhaps you're trying to persist changes to Zope attributes on those nodes? -- Karl Anderson kra(a)monkey.org http://www.monkey.org/~kra/

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(no subject)
by biz＠ebookleader.org 30 Oct '01

30 Oct '01

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ParsedXML in Zclass methods loses permissions on Zope restart
by Brad Clements 30 Oct '01

30 Oct '01

I'm still casting around for a suggestion on where I can go to fix this. I have a ParsedXML object in the methods list of a ZClass Product. The "Access Contents Information" Permission Mapping always get's reset to "blank" in the ParsedXML object when Zope restarts. Is this a problem with ZClasses, or with ParsedXML? I put this in the collector 3 or 4 months ago, and have asked a few times on different lists.. Got no responses. I now must fix it, can't put it off any longer. Any suggestions where to look in the source for where Permission mappings are stored? Perhaps ZClasses stores the permission mappings, but ParsedXML overrides the restored value somehow? Zope 2.3.3 (binary release, python 1.5.2, linux2-x86) (Using last released beta parsed XML) Brad Clements, bkc(a)murkworks.com (315)268-1000 http://www.murkworks.com (315)268-9812 Fax netmeeting: ils://ils.murkworks.com AOL-IM: BKClements

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