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Expressions like <dtml-var this url> bail out contrary to intuition -- proposed fix enclosed
by Jarkko Kniivilä 07 Feb '00

07 Feb '00

Hi fellow Zopistas! While upgrading a Zope 2.1.0 beta installation recently to 2.1.3, I discovered that a recent change made to 'DT_Var.py' rendered DTML expressions like <dtml-var this url> and &dtml.url-this; inoperative. I had been relying on them for a default action url on my forms (in DTML methods). Especially the entity reference syntax is quite a nice abbreviation for the more explicit <dtml-var "this().absolute_url()"> which still continues to work. The enclosed fix simply acknowledges that 'this' isn't a ZODB namespace object but a method encapsulating python 'self' and thus always needs to be invoked. I'm not quite on the top of things why the previous behavior was changed in the first place (Jim? Anyone?). I'll file this to the Collector if there's no objection by you. Copyright to the patch is hereby transfered to Digital Creations to be used freely. Cheers, // Jarkko Kniivila, CTO, Ambient Factor New Media, Hameenlinna, Finland

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Is there a way to find out where a method is defined?
by Andrew Wilcox 07 Feb '00

07 Feb '00

While browsing through Zope and product Python source code, I often see a method being called on an object and want to find out what it's doing and look up the definition. Because Zope objects often have many superclasses, I end up scanning through many class definitions. (My most recent experience was finally finding the definition of this() in the Item class, and saying, oh yes, that's correct, it doesn't do anything :-) And, there's always a danger that I'll miss a definition in a subclass or a superclass that gets inherited first, and be looking at the wrong method definition for the particular object. Is there a way in the runtime or in the debugger, perhaps through the magic of Python reflection, to ask "when I call this method on this object, this is the class providing the definition?"

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Re. Scheduler product, anyone?
by Jerry.Spicklemire＠IFLYATA.COM 06 Feb '00

06 Feb '00

I had to do this just yesterday, and the urllib.py module made it absolutely painless. Here's the simplistic little script I came up with, which could be called by cron, or some other task manager. This ia probably way less cool than the answer you're looking for, but it might give someone else some ideas . . . Later, Jerry S. --------------------------------------------------- """ urlgrabr.py is a simple script to hit an URL, capture the generated output, and manipulate it, based on parameters. e.g. save it as a file, python urlgrabr.py http://server/folder/object file=filename.html Default is simply to request the URL, and exit, dumping all data. """ import urllib import sys import string c_url = sys.argv[1] c_action = None u_url = urllib.urlopen(c_url) if len(sys.argv) > 2 : c_action = sys.argv[2] if string.lower(c_action[:5]) == "file=" : f_action = open(c_action[5:], "w") # file name for l in u_url.readlines() : if string.strip(l[:-1]) : f_action.write(l) f_action.close()

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Zope componentry
by Jeff Bauer 05 Feb '00

05 Feb '00

Hi All. Andrew Kuchling posted the following message on comp.lang.python about his nght2html.py module. His message reminded me that it's a bit of a hassle maintaining code that relies on one or more of the Zope components, compared to the relatively simple way of dealing with Bobo code. [ amk ] > It's perfectly possible to use DTML outside of Zope; > nght2html, the templating system I use for my Web > pages, uses DocumentTemplate because I didn't want > to write and maintain Yet Another templating syntax, > and DocumentTemplate has practically all the bells > and whistles you need. > http://www.mems-exchange.org/software/python/nght2html/ Zope appears to be presently distributed as a single, monolithic package. It was formerly available as downloadable components. (Is there a link to older versions available?) I can understand that Digital Creations does not have the available bandwidth to continue to support distributing individual components. However, I'm interested in developing a long-term strategy that will allow me to continue to use Zope components (ZODB, ZTemplate, etc.) in a portable, low-maintenance kinda way. Jeff Bauer Rubicon Research

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Re: [Zope-dev] Re. Scheduler product, anyone?
by Tres Seaver 05 Feb '00

05 Feb '00

Jerry.Spicklemire(a)IFLYATA.COM wrote > > Loren wrote: > > >... The crontab would run a Zope Dispatcher which would then dispatch > >Zope methods that had been scheduled from within Zope. Thus, Zope would > >acquire cronish capabilities. > > Mark Lesh (Mark, care to add anything?) developed an "event processor" > (pre-Zope) that had similar requirements. Since it had to run on both DOS > and Windows boxes it was done in Clipper, which has the very Pythonish > capacity of calling code "objects" stored as fields of a Clipper table! > > Zope and a standalone Python event loop can easily pass messages in the form > of records in a shared data store, e.g. a PostgreSQL database. > > > ... Do you think it's important to capture output? > > Not in itself, but it is certainly necessary to verify successful completion > of each event, and those events can involve creation of output. ZODB may or > may not be the target storage for such output, but an effective Event > Manager must at least be able to confirm the output's existence and > correctness, currency, etc. > > When an event fails an error event may be generated, whose first purpose is > to attempt to restart the failed event, including verifying and/or > reinitializing any prerequisites. An alert event (auto-page) may also be > generated, to notify the designated driver of a mishap. (Yuck!) > > We found that we needed to track : > > dependencies (conditions required prior to start, such as prior > events) > > normal runtime window (earliest start time, latest end time) > > normal runtime length (shortest expected completion period, longest) > > on-completion action (initiate subsequent event) > > on-error action (re-start event, alert event, etc.) > > >The kinds of scheduled tasks I'm thinking about are > > - email reminders > > - garbage collection > > - updating syndicated content from other sites > > > >Anybody have other examples with other use patterns? > > - promoting new or updated content through develop, test, production status > > - spamming users when new content gets published > > - notifying content maintainers of irate feedback (after spamming users) > > This sort of process may at first appear to fall outside Zope's target > problem domain, but applying Zope to the task of content managment leads > down this path quite directly. A Web Publishing Workflow process readily > maps to an event driven system, each event triggered by the completion (or > failure) of some prior event(s). > > Conceptually, the leap required to see Zope in this light is to think of > each request of an URL as a call to an object / method, not just a pointer > to a displayable Web "page". Jon Udel's Keynote from the Zope Track points > straight to this sort of Distributed Web Object model. > > see : http://udell.roninhouse.com/ZopeKeynote.html I have been thinking about what it would take to add "Events" to Zope, in the vein of the Property/Event/Method model of VB/Delphi/JavaBeans. The "simplest thing that could possibly work" seems to me to inject the "Obseerver" design pattern into Zope's current PropertyManager and ObjectManager classes: * PropertyManager would have installable "event handlers": - 'BeforePropertyUpdate': called just before modifying a property value, passing the object, the property name, the old value, and the new value. This handler could do anything (send mail, write to an external data store, whatever), and would return true if the change was OK (this is actually "observer-with-veto") - 'AfterPropertyUpdate': called after modifying a property value, passing the object, the property name, and the new value (this is a "pure" observer). * ObjectManager would have a set of similar handlers: - 'BeforeChildAdd' - 'BeforeChildDelete' - 'BeforeChildReplace' Something like this approach seems necessary to me to allow for generalize workflow applications in Zope. How workable does this scheme look? Tres. -- ========================================================= Tres Seaver tseaver(a)palladion.com 713-523-6582 Palladion Software http://www.palladion.com

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tracking user usage
by ethan mindlace fremen 05 Feb '00

05 Feb '00

A long time ago in a galaxy far, far, away, a Zopista said that I could easily track user's space utilization. Could someone point me to the hooks or wherever else I need to go to implement something like this? Specifically, I just need to track how big the stuff in a SiteAccess folder gets. (of course, i have to cross-reference that with disk quotas, but that's another kettle of fish) ~ethan fremen (who wishes he could just #include another data.fs from the "parent" data.fs)

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Re: [Zope-dev] Re. Scheduler product, anyone?
by Anthony Baxter 05 Feb '00

05 Feb '00

>>> "Loren Stafford" wrote > The kinds of scheduled tasks I'm thinking about are > - email reminders > - garbage collection > - updating syndicated content from other sites - checking for automated workflow tasks who's preconditions have been met, and executing them. > Because I'm also thinking about repetitive tasks, I'm not anxious to have to > capture the outputs of the scheduled methods. I'd have to add them to the > end of a log file, and have to worry about what happens when more than one > copy of the method is running. I thought I'd expect scheduled methods to > have side-effects, but no STDOUT output, and throw away any output that > might be created. Do you think it's important to capture output? Absolutely. A log file would be _bare_ minimum - ideally, some sort of pluggable logging architecture could be used so that you could slot in a smarter logger. Anthony

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RE: [Zope-dev] ZServer(FCGI) stability
by Amos Latteier 04 Feb '00

04 Feb '00

> Unfortunately our site which runs both under straight ZServer > and through > FastCGI hangs and requires restarting every day. Here is some debuging > info (Zope-2.1.3). I believe that this problem is fixed in the latest version of FCGIServer.py in CVS. If you can't get it from CVS let me know and I'll mail it to you. Please let me know if the latest version does not solve your problem. Thanks! -Amos -- Amos Latteier mailto:amos@digicool.com Digital Creations http://www.digicool.com

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RE: [Zope-dev] Re. Scheduler product, anyone?
by Jerry.Spicklemire＠IFLYATA.COM 04 Feb '00

04 Feb '00

Loren wrote: >... The crontab would run a Zope Dispatcher which would then dispatch >Zope methods that had been scheduled from within Zope. Thus, Zope would >acquire cronish capabilities. Mark Lesh (Mark, care to add anything?) developed an "event processor" (pre-Zope) that had similar requirements. Since it had to run on both DOS and Windows boxes it was done in Clipper, which has the very Pythonish capacity of calling code "objects" stored as fields of a Clipper table! Zope and a standalone Python event loop can easily pass messages in the form of records in a shared data store, e.g. a PostgreSQL database. > ... Do you think it's important to capture output? Not in itself, but it is certainly necessary to verify successful completion of each event, and those events can involve creation of output. ZODB may or may not be the target storage for such output, but an effective Event Manager must at least be able to confirm the output's existence and correctness, currency, etc. When an event fails an error event may be generated, whose first purpose is to attempt to restart the failed event, including verifying and/or reinitializing any prerequisites. An alert event (auto-page) may also be generated, to notify the designated driver of a mishap. (Yuck!) We found that we needed to track : dependencies (conditions required prior to start, such as prior events) normal runtime window (earliest start time, latest end time) normal runtime length (shortest expected completion period, longest) on-completion action (initiate subsequent event) on-error action (re-start event, alert event, etc.) >The kinds of scheduled tasks I'm thinking about are > - email reminders > - garbage collection > - updating syndicated content from other sites > >Anybody have other examples with other use patterns? - promoting new or updated content through develop, test, production status - spamming users when new content gets published - notifying content maintainers of irate feedback (after spamming users) This sort of process may at first appear to fall outside Zope's target problem domain, but applying Zope to the task of content managment leads down this path quite directly. A Web Publishing Workflow process readily maps to an event driven system, each event triggered by the completion (or failure) of some prior event(s). Conceptually, the leap required to see Zope in this light is to think of each request of an URL as a call to an object / method, not just a pointer to a displayable Web "page". Jon Udel's Keynote from the Zope Track points straight to this sort of Distributed Web Object model. see : http://udell.roninhouse.com/ZopeKeynote.html Later, Jerry S.

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ZServer(FCGI) stability
by Pavlos Christoforou 04 Feb '00

04 Feb '00

Hello - Unfortunately our site which runs both under straight ZServer and through FastCGI hangs and requires restarting every day. Here is some debuging info (Zope-2.1.3). Unhandled exception in thread: Traceback (innermost last): File "/usr/local/Zope-2.1.3-src/ZServer/PubCore/ZServerPublisher.py", line 97, in __init__ response._finish() File "/usr/local/Zope-2.1.3-src/ZServer/FCGIServer.py", line 699, in _finish 'log_request')) File "/usr/local/Zope-2.1.3-src/ZServer/FCGIServer.py", line 564, in push if send: self.initiate_send() File "/usr/local/Zope-2.1.3-src/ZServer/medusa/asynchat.py", line 206, in initiate_send self.refill_buffer() File "/usr/local/Zope-2.1.3-src/ZServer/medusa/asynchat.py", line 190, in refill_buffer self.producer_fifo.pop() File "/usr/local/Zope-2.1.3-src/ZServer/medusa/asynchat.py", line 264, in pop del self.list[0] IndexError: list assignment index out of range I suppose I could modify the fifo class in asynchat to check for empty self.list before attempting to index it, but I believe such a situation should not normally arise (ie calling del self.list[0] on an empty list). Seems to me that the problem is with FCGIServer.py. As I need a temporary solution *quickly* I will modify the fifo class and hopefully I won't create more problems ... Any ideas? Pavlos

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