Mailman 3 July 2008 - Twisted

[Twisted-Python] unblocking smtp send?
by Kevin Mateo Lim July 3, 2008

July 3, 2008

My webapp is blocking on this sendmail code that I wrote: from twisted.internet.ssl import ClientContextFactory from twisted.internet.defer import Deferred from twisted.mail.smtp import ESMTPSenderFactory from twisted.internet import reactor import twisted.python import sys import StringIO twisted.python.log.startLogging(sys.stdout) contextFactory = ClientContextFactory() result = Deferred() message_io = StringIO.StringIO(message_str) do_auth = bool(username and password) factory = ESMTPSenderFactory(username, password, from_addr, to_list, message_io, result, contextFactory=contextFactory, requireAuthentication=do_auth, requireTransportSecurity=use_tls) reactor.connectTCP(smtp_host, smtp_port, factory) result.addCallback(lambda ign: reactor.stop()) reactor.run(installSignalHandlers=0) Is there any way I can allow the UI to continue, without blocking on this code? According to the logs, there was a 30second cap between starting factory and stopping: 2008-07-03 13:24:16-0400 [-] Log opened. 2008-07-03 13:24:16-0400 [-] Starting factory <twisted.mail.smtp.ESMTPSenderFactory instance at 0x203d3c8> 2008-07-03 13:24:49-0400 [ESMTPSender,client] Stopping factory <twisted.mail.smtp.ESMTPSenderFactory instance at 0x203d3c8> 2008-07-03 13:24:49-0400 [-] Main loop terminated.

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[Twisted-Python] email addresses with display names in Twisted Mail?
by Kevin Mateo Lim July 3, 2008

July 3, 2008

Hello all, I'd like the emails that I send with my webapp to include the display name. as per http://www.ietf.org/rfc/rfc2821.txt: User Name <local-part@domain> When I try to include this style of address in my sendmail method, I get this error: <class 'twisted.mail.smtp.AddressError'>: Parse error at ' ' of ("'MyDomain Mailer' <no-reply(a)mydomain.com>", [' ', "Mailer'", ' ', '<', 'no-reply', '@', 'mydomain', '.', 'com', '>']) Any suggestions? Because I'm stuck on this. Thanks, Kevin

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[Twisted-Python] "Failure: exceptions.TypeError: exceptions must be classes, instances, or strings..."
by Don Dwiggins July 3, 2008

July 3, 2008

I'm running an xmlrpc server, frozen with py2exe. I'm getting an error message in the log file that reads: > 2008/07/02 18:14 -0700 [-] Unhandled Error > Traceback (most recent call last): > Failure: exceptions.TypeError: exceptions must be classes, instances, or strings (deprecated), not type ... and that's it: no traceback, no line number, no indication where the problem occured. (I'm running Twisted 2.5.0, if it makes a difference.) Any idea what I can do to make it be a bit more informative? Thanks, -- Don Dwiggins Advanced Publishing Technology

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[Twisted-Python] job posting: Flumotion
by Thomas Vander Stichele July 3, 2008

July 3, 2008

Hi everyone, I wanted to announce some new positions at Flumotion. We're looking for up to three "core" developers and a web developer. The core developer position involves Python and Twisted all the way; for the web developer position it depends on the team's choice (currently python and Django is being used a lot) We're looking for talented, motivated and passionate developers who want a healthy mix of working on a real commercial product and platform, and the Free Software technologies they're based on. Flumotion is a Spanish company, located in Barcelona, and part of the Fluendo group. Flumotion is our UNIX-based streaming server, written in Python, on top of GStreamer and Twisted. Our platform is a collection of Linux servers distributed over Spain, as we're looking to expand our business further into Europe. It handles several Gbit/s of streaming traffic. We are also working on a commercial version of Flumotion, to be released later this year. We are looking for developers to: - work on the core technology: the server, GStreamer integration, the platform, scalability - work on the box project: web frontend, usability - work on the web projects: our website, our customer portal, and our backoffice If you like working with other hackers, on real-world projects, while looking out over the sea and enjoying the good weather of Barcelona, contact us! Feel free to drop me a mail at thomas (at) flumotion (dot) com if you prefer to drop off your CV in a more human mailbox. For more information, as well as complete job descriptions, see our Hiring page: http://www.flumotion.com/en/hiring/ -- Now wait a minute... you think I'm evil... if I bring a group of girls on a camping trip and don't touch them? -- GStreamer - bringing multimedia to your desktop http://gstreamer.freedesktop.org/

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[Twisted-Python] stopping daemon started via twistd
by Jeff Dyke July 3, 2008

July 3, 2008

I'm looking for a portable way to stop and start a twisted application, specifically a twisted.web.xmlrpc server being started with a .tac file via twistd. on ubuntu i can easily use the start-stop-daemon but some other developers are using mac/windows and i was looking for a nice way for all to be able to start and stop this server as they make changes to it, aside from kill/killproc that is. I noticed that the object returned after calling internet.SSLServer server has a method called stopService, but am confused about how to use that, after starting it with twistd. Perhaps twistd is not the right approach for starting? googling around seems to bring up arguments from years past about if this behavior belongs in twisted on in the users app, but found no real solution...but may have missed the obvious. Thanks Jeff

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[Twisted-Python] Tie two event loops
by Paul Wilson July 2, 2008

July 2, 2008

Hi all, I'm new to twisted but am having trouble getting my head around how to structure my application with this new approach. I'm creating a server that accepts client connections and then drives the client according to a simple, line-oriented protocol. The server sends the request (1 line), and receives a single lined result. I'd like the server to offer an API to generate the correct request lines to the client, and return the results (either blocking or asynchronously). So in effect, I have two event loops, one from the Network and one from whatever's sending the API requests (command line?). Can anyone offer any guidance on how to tie these two parts together? My instinct is to have the two event loops in separate threads and communicate through Queue.Queue, but that doesn't seem to follow the spirit of twisted. And I guess I'd have to somehow tell the reactor to poll the Queue object for requests, and then dispatch it to the relevant method to send out to the client. I've looked at threadedselectreactor but can't seem to find any decent documentation to even decide if it's write for what I want. Any advice would be much appreciated. Thanks, Paul

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Re: [Twisted-Python] ZSI using Twisted Web Server
by Christopher Armstrong July 2, 2008

July 2, 2008

On Tue, Jul 1, 2008 at 7:06 AM, Torsten A. <c2k_list(a)gmx.de> wrote: > Whenever I connect to the baseWS, the render-function is called and > deligates the request to render_POST(), which I created. In render_POST() I > can access the SOAP-Envelope via request.content.read(), just as supposed > to. Now, since I have the plaintext SOAP-Envelope, I need ZSI to parse it, > extract the functions and argument of the envelope (RPC call) and call the > corresponding function. I just cannot figure out where to start in ZSI. > > Can someone help me out which function to call/ class to create? I just want > to enter the ZSI process where this step is done and then give control to > ZSI, as if it received the SOAP-envelope from its own webserver. It sounds like you've figured out the Twisted side alright, but you don't know how to use ZSI's APIs to do what you want. Perhaps you should ask the ZSI community about that. FWIW, I'd love to see twisted.web.soap to be updated to use ZSI, since it's still using the crappy SOAPpy. If you come up with a general soap service layer like twisted.web.soap, it may be interesting to include it in Twisted. -- Christopher Armstrong International Man of Twistery http://radix.twistedmatrix.com/ http://twistedmatrix.com/ http://canonical.com/

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[Twisted-Python] Re: Twisted Hosting and Twisted in the Cloud
by Andrew Francis July 2, 2008

July 2, 2008

Hello Duncan: >If you do, what kinds of apps (that you are currently running) do you >want to be able to run in such environments? Simple web sites? DNS >servers? Game servers? Chat applications? Web/data services apps? Well I have been working on WS-BPEL (Web Service - Business Process Execution Language) processor prototypes. >And lastly, what hosting companies are your favorites? Where would you >be happiest, if they supported Twisted? Would you consider switching >to a hosting provider that *did* support Twisted? I have been looking at Amazon EC2. A part of EC2's appeal is that there are other services that I would use (i.e., SQS). I haven't looked into the EC2 environment in depth but I just assumed that I would have to set up Twisted as well as Stackless Python as a part of a custom AMI. Cheers, Andrew

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Re: [Twisted-Python] Returning a DeferredList?
by Terry Jones July 1, 2008

July 1, 2008

>>>>> "Nathan" == Nathan <nathan.stocks(a)gmail.com> writes: Nathan> Oh, ok. My apologies, Terry. Thanks - but no need! Nathan> After staring for awhile I think I figured out what's going on. Nathan> First, everywhere I use this method in real code is to provide a Nathan> final AMP response (which is why it works for me). I think what Nathan> Jean Paul meant was that the AMP code looks at the object that the Nathan> AMP responder returns, and if that object is a deferred, then the Nathan> underlying AMP code (that you don't normally see) waits for the Nathan> deferred's callback value and uses that as the actual return value Nathan> of the AMP responder. I've not looked at the code (maybe you should! :-)) but that sounds right. And it would probably do this by just adding another callback to the deferred. Nathan> I had mistakenly taken this as a more general method of Nathan> returned-deferreds-resolving-into-their-callback-values, which is Nathan> why everyone is taking issue with my hasty AMP-less pseudo-code. That sounds right. Nathan> I must say, I've had more trouble grasping the nuances of deferreds Nathan> and other twisted objects than any other framework or language I've Nathan> ever worked with. I also spend much more time _in vain_ going Nathan> through the docs and api reference than other languages. At least Nathan> there's a great mailing list! I know the feeling. I've found it helpful to read the various Deferred pages quite a few times through, to play with toy examples to see the flow of control, and also to read the source of defer.py (which isn't complex and which I think is elegant). Nathan> So back to my original task -- I'm trying to get that same behaviour Nathan> in AMP when using a deferred list -- but I could probably just create Nathan> a deferred and return it as the AMP response (because AMP will wait Nathan> for the deferred's callback value), and then fire a callback with my Nathan> correct answer once I've processed my deferred list. Thus, I could Nathan> avoid figuring out how AMP handles Nathan> deferred-lists-returned-from-responders altogether. That sounds right too. It might help to know that a DeferredList is just a subclass of Deferred. So when you return a DeferredList, you're in fact returning something that behaves like a regular Deferred. When its callback is fired, it gets a list of status & results from all the deferreds in the originally passed list. So if AMP knows how to handle deferreds, it can certainly handle a DeferredList too. Nathan> Have I got it straight now? Yep, sounds like it. Terry

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Re: [Twisted-Python] Returning a DeferredList?
by Terry Jones July 1, 2008

July 1, 2008

>>>>> "Nathan" == Nathan <nathan.stocks(a)gmail.com> writes: Nathan> I regularly use the return values of deferreds to simulate Nathan> synchronous behaviour like this: [snip] Nathan> So now I'm trying to do the same thing with DeferredList's, but Nathan> apparently the semantics aren't the same. Here's some actual Nathan> runnable sample code trying to use the DeferredList: Hi Nathan You're not using deferreds properly. In the simple/typical case, when you call a function that returns a deferred, you will want to add (at least) a callback to that deferred. The callback then gets called with the value that is being passed down the callback chain. Change your code to the below and it works. Your original code appears to work only because you're testing a deferred result in a Boolean context, which takes you to the true part of your if. You need to add call/errbacks to the deferred there too. Terry --- from twisted.internet import reactor, defer def callback_function(results): return "(--> This is the value that I want to get into retval! <--)" def make_a_list(): deferred1 = defer.Deferred() deferred2 = defer.Deferred() dl = defer.DeferredList([deferred1, deferred2]) dl.addCallback(callback_function) deferred1.callback('one') deferred2.callback('two') return dl def test(): def cb(val): print "retval is:", val make_a_list().addCallback(cb) reactor.callWhenRunning(test) reactor.callLater(2.0, reactor.stop) reactor.run()

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