Mailman 3 May 2006 - Twisted

[Twisted-Python] Twisted Python 0.7.0 Prerelease Testing
by Glyph Lefkowitz 05 Aug '21

05 Aug '21

hi there, folks: I'd really like to release 0.7.0 but I would like it to be at least a little bit tested before I do so. Could those of you with CVS trees check everything out and see if it performs as advertised? Deeper bugs than that will have to wait for the next release, but I'd at least like to know if it works for someone other than me. Thanks. ______ __ __ _____ _ _ | ____ | \_/ |_____] |_____| |_____| |_____ | | | | @ t w i s t e d m a t r i x . c o m http://www.twistedmatrix.com/~glyph/

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[Twisted-Python] Get IP of connecting client in XMLRPC server
by Remy C. Cool 28 Apr '13

28 Apr '13

Hello, On 18 May 2004, the following message was posted to this mailinglist: Jp Calderone exarkun at divmod.com wrote: >Daniel Newton wrote: > > I have a simple XML-PRC server similar to the example below: > > from twisted.web import xmlrpc, server > > class Example(xmlrpc.XMLRPC): > """An example object to be published.""" > > def xmlrpc_add(self, a, b): > """Return sum of arguments.""" > return a + b def xmlrpc_whatIsMyAddress(self): return self.transport.getPeer().host > > if __name__ == '__main__': > from twisted.internet import reactor > r = Example() > reactor.listenTCP(7080, server.Site(r)) > reactor.run() > > I want to be able to get the address of the client that calls the xmlrpc > method can anyone help me with this? This solution didn't work because 'transport' isn't a property of the Example class. I'm currently in the process of changing from a customized SimpleXMLRPCServer to a twisted XMLRPC server solution and I need to insert the client IP into the attributes passed to the called xmlrpc method. Anyone who knows the answer and is willing to share the info? Regards, Remy

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[Twisted-Python] Problem: spawnProcess() never ending when installSignalHandlers=False
by Matt Feifarek 03 Feb '07

03 Feb '07

Hello. I'm using Twisted 1.3.0 on python2.4 on an Ubuntu-Hoary x86 Linux box. I'm using twisted and spawnProcess() with a Queue structure to chain processes that need to be called (specifically, imagemagick commands). I use the "processEnded" event/method of t.i.p.ProcessProtocol to go from one task to the next. Twisted shares a python process with a multi-threaded web-app-kit (Webware) so it has to be run in a thread. This worked well on other older versions of twisted and older versions of python; also on linux. I've tracked down the problem to be twisted itself (or my incorrect use of it) rather than my code. This example illustrates it: ------------------------------------------------- from twisted.internet import reactor from twisted.internet.protocol import ProcessProtocol class MyProt( ProcessProtocol ): def processEnded(self, reason): print "ended.", reason executable = '/bin/touch' args = ( '/tmp/foo.txt', ) args = (executable,) + tuple(args) reactor.spawnProcess( MyProt(), executable, args ) reactor.callLater( 5, reactor.stop ) #reactor.run() reactor.run(installSignalHandlers=False) ------------------------------------------------- As is, this code never runs the "processEnded()" method of MyProt(). If I change the reactor.run() parameter to leave the signal handlers on, it works. Note that I need to leave the signal handlers turned off because I can't run the reactor in the main thread; Webware needs that. I also know that the subprocess is giving up its file descriptors; I can see that if I put more print statements into MyProt(). And I know that the subprocess is working; /tmp/foo.txt is there. It seems that somehow the reactor is using signals to notice when a process has ended; this makes a certain ammount of sense intuitively, though I don't understand the nitty-gritty of processes and signals at all. And more importantly, this has worked before on other combinations of twisted/python. Is this a bug? If so, has it been fixed? If not, what should I do to detect when a spawned process is finished? Thanks very much. Twisted rocks.

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[Twisted-Python] Service dependencies
by Matt Goodall 10 Jul '06

10 Jul '06

Hi, I have a couple of services. The second is dependent on the first being fully initialised before the second gets set up. I thought that the order of Service startup was typically handled by organising services in a hierarchy, and that the startup of the hierarchy understood deferreds. I was wrong - service.Application is a MultiService and only understands deferreds in stopService. There's a DependentMultiService class in twisted.internet.app but that entire module has been deprecated. Is there a reason why the MultiService does not support deferreds in startService? Is there a reason that DependentMultiService was not moved across to the twisted.application package? In other words, what is the recommended way of starting services in the correct order, including waiting for them to get initialised fully, these days? Thanks. - Matt -- __ / \__ Matt Goodall, Pollenation Internet Ltd \__/ \ w: http://www.pollenation.net __/ \__/ e: matt(a)pollenation.net / \__/ \ t: +44 (0)113 2252500 \__/ \__/ / \ Any views expressed are my own and do not necessarily \__/ reflect the views of my employer.

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[Twisted-Python] Status of wxPython support in Twisted 2.1: use wxreactor
by Itamar Shtull-Trauring 01 Jul '06

01 Jul '06

wxreactor in Twisted 2.1 uses threadedselectreactor. This means that wx apps ought to use wxreactor, not TSR directly; there are some issues with vanilla TSR wx integration that are also present in wxreactor, but will be fixed in future versions of wxreactor. What's broken (there may be more): 1. reactor shutdown events aren't handled correctly (e.g. Deferred returned from during-shutdown event). 2. Signal handling for e.g. Ctrl-C is caught by wx, not twisted. In order to get these fixed I need your help. I have a version of wxreactor that *probably* fixes these in Subversion trunk. You can try it out by running doc/core/examples/wxdemo.py. Hitting Ctrl-C, choosing Exit from the menu or closing the menu all should have the same effect - the application logs "shutting down in 0.3 seconds...", "2", "1", "0" then exits. In addition, "Hello world" should continue to be printed while the dialog box is open or you are holding down a menu. Please try this out, and report success or failure at <http://twistedmatrix.com/bugs/issue1235>. I'm especially interested to hear if it works on Windows or Mac OS X. Please include your OS and version of wxPython/wxWidgets when submitting reports.

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[Twisted-Python] can pb.Copyable objects be compared for equality after a round trip?
by Robert Gravina 28 Jun '06

28 Jun '06

Twisted-list, In an application I'm writing I would like all Perspective Broker clients to share some list of objects and have them all keep in sync when one of the clients updates an object's attributes (imagine say a shared address book - I'm not creating an address book, but it's easier than explaining the details of my app). I've created a pb.Cacheable class for the purposes of notifying clients when new objects are added to this list which works fine (I based this on the cache_classes.py example from the docs here <http://twistedmatrix.com/ projects/core/documentation/howto/pb-copyable.html>). Where I am having trouble is with round trip editing these objects (which are all both pb.Copyable and pb.RemoteCopy - I did this so that I wouldn't have problems of accidentally storing a RemoteFoo object in my ZODB rather than a Foo object). Say one user edits one of the objects (e.g. changes the name/phone number etc. of one of the entries in the shared address book). and then I callRemote to some method like "updateObject" on the users Avatar and pass this object to this method. According to the doc page I mentioned previously "Copyable objects return unchanged from a round trip", but when I check if the object is in the list on the server it thinks it isn't there. In fact, they seem to point to different objects in memory, so naturally a "if object in list" statement will fail. Am I checking for equality in the wrong way? Or am I approaching the problem in the wrong way? I am quite new to Twisted, so I apologise if the problem is obvious. Robert

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[Twisted-Python] PB and other distributed object protocols
by Stephen Waterbury 17 Jun '06

17 Jun '06

Hi Gang, Preface: I'm not a protocol guru, or even a "distributed object" (DO) guru, so this message is from the point of view of a DO novice looking for insights from some of the twisted minions (/gurus) and other cybergods who hang out here. I've been monitoring Brian's work on newpb (PBng?), and I love everything about it. Except how long it's taking. :( Brian: I know you have a real job, too, so I completely understand! (Incidentally, you're the only one whose commit messages I save, because they're always so well documented.) I've read the TODO list, and pretty much everything is beyond my abilities (and time) to contribute to -- sorry! -- but is it possible to put any kind of approximate timeline on some of it? PB is what I really want to use for my project, but I need something that's close to ready-for-prime-time, and I've been waiting literally years for PB, so in the meantime I'm looking at other candidates. I would definitely prefer a "twistable" technology -- i.e., one for which some kind of async adapter can be written from twisted -- and also one that has bindings for other languages (mainly Java, since my organization is Java-heavy). I've dismissed the idea of CORBA -- although one or more of the python orbs is probably twistable, CORBA has such a negative image that I'd probably have to lie about using it, and it does have lots of weird baggage. [Aside: I always liked Bill Janssen's ILU (how could you not like a distributed object system that had bindings for both python and lisp??) and I was sad to see it go. Interesting that Bill is now in the Python community.] Over the weekend I read the docs for ICE (http://www.zeroc.com/), sort of a streamlined, WAN-optimized CORBA. It has nice features, and even support for (threaded) async operations which seems (to my novice understanding) twistable. But its type system and python binding seem very unpythonic to me, based on lots of C++-isms, etc. Ugh. I just today discovered "json-rpc", which looks pretty cool. I currently use xml-rpc in my twisted app, and I've thought that json would be a neat replacement for xml (more concise + very pythonic syntax so probably *way* more efficient python marshalling/unmarshalling). And someone finally did it -- great! Has anyone here experimented with it? Anyone thought about twistifying it? If not, I might take a stab (I'd start by looking at what Itamar [I think] did with xml-rpc). Cheers, Steve

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[Twisted-Python] Synchronous Code Fishbowl
by Ed Suominen 15 Jun '06

15 Jun '06

The dialogue copied below shows yet another example of the frustrations that arise when trying to bridge the chasm between Twisted and the synchronous rest of the world. This latest episode inspired the idea of a synchronous code fishbowl that offers well-behaved Twisted code a deferToQueue() method for running badly-behaved blocking code. See http://foss.eepatents.com/sAsync/browser/branches/syncbridge.py Comments? - Ed Suominen -------- Original Message -------- Michael Bayer wrote: > why are you using twisted *with* threads ? didnt we all agree that was > sort of unnecessary ? Twisted operates without needing to run *in* a thread by doing everything asynchronously. Every call made via the Twisted event loop must either return (synchronous) results very quickly or return an immediate reference to an eventual result (thus operating asynchronously). The objects that hold those immediate references are called "deferreds" in TWisted parlance. Twisted runs most all of its internal operations with appropriate chunking and use of select() to keep the asynchronous event loop humming along nicely, but it has no control over how other libraries do things. When an external library like SQLAlchemy presents a blocking call like select(...).execute.fetchall(), the only way to make that call "play nice" with Twisted by immediately returning a deferred to the eventual result is by having TWisted run it in a thread. It includes the deferToThread() function for that express purpose. > (this goes to my point that twisted is a pain in the butt...) Perhaps, but asynchronous code is a whole different way of thinking that some of us actually find cleaner and more intuitive than blocking + threads. What I'm trying to do with sAsync is put the "pain in the butt" associated with making synchronous and asynchronous code work together firmly behind the scenes for Twisted users, at least as far as interacting with SQLAlchemy is concerned. > anyway, SA 0.2 uses the same idea for sqlite threading as 0.1....it > maintains each connection thread locally since you cant share a sqlite > connection between threads. im also not sure what youre talking about > with a "thread local copy of the engine", if thats something youre doing > on your end, you might want to not do that. use Connection objects > instead theyre much more portable. Mike, I remember you telling me a while ago that SA somehow figures out how to make things work with the engine. That was after I spent a lot of time trying to re-engineer the wheel, to great frustration on my part. I followed your advice, ditched my thread-local code, and got SA transactions just fine (based on the engine) to run in arbitrary threads. Now it's not working in SA 0.2. Could you point out what's changed in regard to the engine vs. threads vs. sqlite? I'd rather not change everything under the hood (e.g., using connections somehow) if I don't have to. The lesson of not trying to re-engineer what SA handled fine on its own is still with me. :-) Best regards, Ed > On May 27, 2006, at 6:57 PM, Ed Suominen wrote: > >> My sAsync project relies on Twisted to maintain a thread pool. It runs >> database transactions in some available thread via Twisted's >> deferToThread() function. See the transact function in >> http://foss.eepatents.com/sAsync/browser/trunk/sasync/database.py for >> details. >> >> That arrangement created no problem with SQLite and SA 0.1, even though >> SQLite does not allow sharing of connections between threads. Somehow, >> SA 0.1 made the transaction run in its thread with a thread-local copy >> of the engine and table that was created in the main thread. I never >> figured out how, but it just worked. >> >> It doesn't work in SA 0.2, however. I either get the error when trying >> to use the main-thread table in the threaded transaction, or have no >> table available in the thread because it wasn't created there. Now I'm >> trying to figure out how to put humpty dumpty back together again. Any >> suggestions? >> >> Best regards, Ed

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[Twisted-Python] twisted and PyQt4
by scalet＠yebu.de 10 Jun '06

10 Jun '06

Hi, it seems to me, there is no reactor for PyQt4 yet. What is the preferred way to have a PyQt4 application using the famous twisted framework for networking. Thanks for any hints. Karl

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[Twisted-Python] Do Twisted support LMTP servers?
by Jesus Cea 06 Jun '06

06 Jun '06

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Twisted is very extensive in protocol support, managing smtp, pop3 and imap4, for example. I was wondering if there is any LMTP server project out there. It should be fairly simple, since LMTP is very very similar to usual SMTP. I need to use LMTP for a local project, and I was wondering if tiwsted could be used to fill this gap. - -- Jesus Cea Avion _/_/ _/_/_/ _/_/_/ jcea(a)argo.es http://www.argo.es/~jcea/ _/_/ _/_/ _/_/ _/_/ _/_/ jabber / xmpp:jcea@jabber.org _/_/ _/_/ _/_/_/_/_/ _/_/ _/_/ _/_/ _/_/ _/_/ "Things are not so easy" _/_/ _/_/ _/_/ _/_/ _/_/ _/_/ "My name is Dump, Core Dump" _/_/_/ _/_/_/ _/_/ _/_/ "El amor es poner tu felicidad en la felicidad de otro" - Leibniz -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2.2 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iQCVAwUBRDb7+plgi5GaxT1NAQK4rQP9EDdkMc0b83teXKB/XM22fV2gq3z/uEj1 RBjeHGSPOs5ogg1+/E4eiq8vq83mNTBDzxVJriN20UbrHgOcC+kBjfnCB8MCPnER 1tEorRnb19Siy+xnu0+rJ3XtNLJXJubMiXxm/5ig27Hl+UChnQLCthiqL1h0P22/ yi9LCprkRZ4= =fG6b -----END PGP SIGNATURE-----

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