Mailman 3 October 2001 - Twisted

[Twisted-Python] Hooking up XML-RPC to twisted...
by Itamar Shtull-Trauring 14 Oct '01

14 Oct '01

...turned out to be trivial. The following is example code (depends on latest CVS since twisted used to reject unknown content-types.) =================================================================== """Hook up an object to XML-RPC. An example session: >>> s= xmlrpclib.Server('http://localhost:7080/') >>> s.echo("lala") ['lala'] >>> s.echo("lala", 1) ['lala', 1] >>> s.echo("lala", 4) ['lala', 4] >>> s.echo("lala", 4, 3.4) ['lala', 4, 3.3999999999999999] >>> s.echo("lala", 4, [1, 2]) ['lala', 4, [1, 2]] """ from twisted.web import resource import xmlrpclib class XMLRPC(resource.Resource): isLeaf = 1 def __init__(self, perspective): resource.Resource.__init__(self) self.perspective = perspective def render(self, request): args, methodName = xmlrpclib.loads(request.content) method = getattr(self.perspective, "perspective_%s" % methodName) return xmlrpclib.dumps((apply(method, args),)) class test: def perspective_echo(self, *args): return args def main(): from twisted.internet.main import Application from twisted.web import server app = Application("xmlrpc-test") app.listenOn(7080, server.Site(XMLRPC(test()))) app.run(0) if __name__ == '__main__': main()

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[Twisted-Python] Help, I've run and I can't fall down!
by Kevin Turner 13 Oct '01

13 Oct '01

Okay. Someone wanna explain to me why this script prints "Duplicate Shutdown Ignored." and sits there instead of exiting? Ctrl-C does seem to work though: > Starting Shutdown Sequence. > Select loop terminated. -- Kevin Turner <acapnotic(a)twistedmatrix.com> | OpenPGP encryption welcome here The moon is waning cresent, 24.7% illuminated, 24.6 days old. #!/usr/bin/env python #$Id: fresh-loginfo.py,v 1.1 2001/10/12 17:49:04 acapnotic Exp $ import os, string, sys from os import path from twisted.spread import pb from twisted.internet import main import pidutils TRUE=(1==1) FALSE=not TRUE cvs_pid = pidutils.findParentNamed('cvs') cvsroot = os.environ['CVSROOT'] file = sys.argv[2] module = string.split(file,'/')[0] def connected(object): object.trackPid(cvs_pid, cvsroot, file) main.shutDown() # sys.exit(0) def aint(reason): sys.stderr.write("fresher didn't connect:\n%s\n" % (reason,)) main.shutDown() # sys.exit(1) pb.getObjectAt("unix", path.join(cvsroot, 'CVSROOT',".freshcvs"), connected, aint) main.run()

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[Twisted-Python] teud and __all__
by Glyph Lefkowitz 12 Oct '01

12 Oct '01

Could the Teud repository please move to somewhere else on Zaibach? I don't particularly want to get commit messages for it, since it's a totally distinct project from Twisted and it's difficult to sort out the messages if they're both coming from twisted-commits. This could also be fixed by Kevin if the commit script were slightly different. Also, about the __all__ attribute... might I suggest that this is a poor choice of names, since this already means something to the interpreter? __teud__ might be a better way to put it. Certainly __init__.py's shouldn't have an __all__ in them that describes classes (or modules) to *document*. Thanks, -- ______ you are in a maze of twisted little applications, all | |_\ remarkably consistent. | | -- glyph lefkowitz, glyph @ twisted matrix . com |_____| http://www.twistedmatrix.com/

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[Twisted-Python] Re: [medusa] Twisted, medusa, ZServer, and VFS's
by Skip Montanaro 11 Oct '01

11 Oct '01

Donovan> ZServer grew out of Medusa.... I'm not sure how tightly tied to Donovan> Zope it is.... Not tightly at all. I use it completely independent of Zope. Donovan> My problem with Medusa is its http and ftp servers assume that Donovan> the VFS can deliver files wrapped in producers without Donovan> blocking. I believe Sam Rushing has said all along that Medusa is intended for I/O-bound situations. If you have producers that are computationally bound or that do I/O outside of the Medusa framework, you'll suffer. -- Skip Montanaro (skip(a)pobox.com) http://www.mojam.com/ http://www.musi-cal.com/

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[Twisted-Python] A problem with threads
by Itamar Shtull-Trauring 11 Oct '01

11 Oct '01

Threadpool should have a function that lets you run a function in a thread and have the result passed to a Deferred object's callbacks. The callback functions in the Deferred should be run in the a thread-safe way. There two alternatives: 1) Run the callbacks in the main event loop thread, which means using twisted.internet.threadtask. This adds a dependency on twisted.internet for twisted.python. 2) Have the user implement the thread-safety stuff themselves. I think (1) is the best way, otherwise you end up having to do a lot of work everytime you use callbacks. But then there's the dependancy issue...

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[Twisted-Python] Teud ready for first public release
by Itamar Shtull-Trauring 11 Oct '01

11 Oct '01

Well, I think teud is ready to go - only remaining issue is that the scripts are chmoded to 777 by distutils, and I have no idea why.

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[Twisted-Python] General Alert: Web Site is Funny
by Moshe Zadka 11 Oct '01

11 Oct '01

What happened to the web site?

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[Twisted-Python] DUH!
by j.her＠t-online.de 10 Oct '01

10 Oct '01

jh@zaibach:~/public_html/teud$ PYTHONPATH=/twisted/Twisted:$PYTHONPATH teudxml Twisted twisted ==> http://twistedmatrix.com/users/jh/teud/Twisted/.idx and then jh@zaibach:~/public_html/teud/Twisted$ for i in *.xml; do 4xslt -o ${i/.xml/.html} $i ~/share/teud/samples/default.xsl; done ==> http://twistedmatrix.com/users/jh/teud/Twisted/twisted.html

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[Twisted-Python] naming conversational methods
by Kevin Turner 10 Oct '01

10 Oct '01

Generally in an object model, if I'm an object, my methods are things I do. If someone says kevin.run(), I run. If they say kevin.jump(height), I jump, and if they say kevin.watch(), I keep my eyes open. But if a perspective is addressing me me through a viewpoint, how should my methods which act upon her be named? If she says to herself, "Self, listen to Kevin," that seems natural to write as self.listen(kevin). Except, in order for her to listen to me, she needs to have me add her to my list of my audience members. So how does her listen method address me? Not as kevin.listen(), because she's the one listening, not me. kevin.speak()? No, she's not commanding me to speak, she just wants to know in the event that I do. kevin.speakTo() seems odd without an object. Someone else could say kevin.speakTo(her), but what she really means is kevin.speakToMe(). Does that work? class Kevin(pb.Viewable): def view_speakToMe(self, perspective): """I will now speak to she who invoked this method.""" # Does it make sense that the personal pronoun in "speakToMe" # refers not to *me*, but to the perspective's owner? # Or does a passive phrasing make more sense? def view_beListenedTo(self, perspective): """This perspective will be listening to me.""" -- Kevin Turner <acapnotic(a)twistedmatrix.com> | OpenPGP encryption welcome here The moon is waning cresent, 46.0% illuminated, 22.5 days old.

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[Twisted-Python] Twisted, medusa, ZServer, and VFS's
by Donovan Baarda 10 Oct '01

10 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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