Mailman 3 November 2009 - Twisted

[Twisted-Python] Twisted 9, do you want it
by Christopher Armstrong Nov. 11, 2009

Nov. 11, 2009

I'm working on it. The core NEWS file is done I think. NEWS for other projects will be worked on tomorrow. -- Christopher Armstrong http://radix.twistedmatrix.com/ http://planet-if.com/

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[Twisted-Python] Need help with Twisted. Please
by Galina Kistanova Nov. 10, 2009

Nov. 10, 2009

Dear Twisted developers, I am not a developer, and definitely need you advice. I use Twisted 8.2.0 on Ubuntu 9.04 and on MAX Snow Leopard to set up Buildbot. One of tests for Buildbot returns an error: Traceback (most recent call last): Failure: twisted.internet.error.ProcessTerminated: A process has ended with a probable error condition: process ended with exit code 1 I am getting the same error both on Ubunty and Leopard. Please advice what could be wrong here? What does it mean “twisted.internet.error.ProcessTerminated: A process has ended with a probable error condition: process ended with exit code 1”? Thanks Gal ________________________________ From: Galina Kistanova Sent: Tuesday, November 03, 2009 1:23 PM To: twisted-python(a)twistedmatrix.com Subject: twisted.internet.error.ProcessTerminated, exit code 1? Hello all, I ran into issue with Twisted, could anybody help me? I have Twisted 8.2.0 on Ubuntu 9.04. I run tests for Buildbot 0.7.11p3 and one of the tests completed with the next error: [ERROR]: buildbot.test.test_locks.Locks.testLock3 Traceback (most recent call last): Failure: twisted.internet.error.ProcessTerminated: A process has ended with a probable error condition: process ended with exit code 1. Cannot find any information what could cause this. What “exit code 1 “ means? I tried to stop MsAfee, but this did not help. Thanks Gal

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[Twisted-Python] Twisted synchronous and asynchronous db connections
by Doug Farrell Nov. 10, 2009

Nov. 10, 2009

Hi all, Our projects at work include synchronous applications (short lived) and asynchronous Twisted applications (long lived). We're re-factoring our database and are going to build an API module to decouple all of the SQL in that module. I'd like to create that API so both synchronous and asynchronous applications can use it. For the synchronous applications I'd like calls to the database API to just return data (blocking) just like using MySQLdb, but for the asynchronous applications I'd like calls to the same API functions/methods to be non-blocking, probably returning a deferred. Anyone have any hints, suggestions or help they might offer me to do this? Thanks in advance, Doug

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Re: [Twisted-Python] Twisted webserver performance issues
by Tom Leys Nov. 9, 2009

Nov. 9, 2009

Thanks for the link info. I literally just set up Varnish for the first time on my web host, so I am no pro. However, varnish uses a c like scripting language that can run regexps on the incoming urls and apply rules to them. What this means is that we can (as a starting point) choose caching times for each of those high traffic urls in the varnish script without touching trac. In the script, we match the front page (with a regexp) and add a max-cache time to 86400, cache it, etc. See http://www.catalystframework.org/calendar/2008/14 for a great varnish tutorial By doing that for each of the urls you listed (bar the timeline, which should be cached for 1 hour or perhaps 30 minutes instead) we will seriously lighten the load on the database and the webserver, even if varnish runs on the same machine (as a start). Every other url (which doesn't have caching set) we could just cache for 30 minutes (perhaps even a day), but only for anon users (no cookies set in browser) -Tom >> On 10:41 pm, leyssw(a)ihug.co.nz wrote: >> >>> Isn't the simplest option to place a decent reverse proxy between the >>> webserver and our clients? >>> >> Possibly so! I gave this a half-hearted attempted a few weeks ago but >> quickly gave up. If someone who is familiar with configuring such a >> proxy would like to help out, perhaps we can get something useful up >> and >> running. >> > > Actually, I just looked at Varnish again and remembered that because of > the way trac sessions work, it's really hard to figure out what may and > may not be correctly cached. I don't know how to resolve this without > serious changes to trac itself. > > Jean-Paul > > > > ------------------------------ > > _______________________________________________ > Twisted-Python mailing list > Twisted-Python(a)twistedmatrix.com > http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python > > > End of Twisted-Python Digest, Vol 68, Issue 13 > ********************************************** > >

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[Twisted-Python] PyObjC and Twisted command line script
by Jonathan Stoppani Nov. 9, 2009

Nov. 9, 2009

Hi All, I just set up a script to do a video recording from my iSight using the pyobjc bridge and the QTKit framework. This script uses the AppHelper.runConsoleEventLoop (not the AppHelper.runEventLoop) function to start his main event loop. I'd like to integrate this script with an existing twisted application but I have trouble to bring it to work. The application is a command line based twisted application managed via AMQP (no user interaction is needed) and started using the twistd command. I tried to install the cfreactor but without success as I have to use the runConsoleEventLoop. Any insights on this? Thanks in advance, ~Jonathan -- Best Regards, Jonathan Stoppani

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[Twisted-Python] Twisted web
by Simon Pickles Nov. 9, 2009

Nov. 9, 2009

Hi all, I am returning to twisted after an extended absence, and was wondering what the status is with twisted's web framework? Is this an active area of development? Also looking forward to Twisted9..... :) Many thanks Simon

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[Twisted-Python] Volunteer for twisted code Reviews and Commits
by David Lyon Nov. 9, 2009

Nov. 9, 2009

Hi All, Glyph mentioned on python-dev that he was after assistance with code reviews. I would like to offer some assistance. I've been developing python for some time and I have a knowledge of prior C++ async patterns such as ACE. More currently I have a reasonable knowledge of protocols such as jabber and so forth. If there is any way that I might be of assistance, please don't hesitate to ask. David

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[Twisted-Python] Daemon processes on windows
by Brian Granger Nov. 9, 2009

Nov. 9, 2009

Hi, I have a server-like process that uses twisted. I need it to daemonize itself and on linux/os x I am simply using the daemonize function from twistd. This works fine. What about Windows though....I saw that the win32 version of twistd doesn't have (unless I am missing it) the ability to daemonize a process. Is is simply impossible to daemonize a process on windows? If so, is there any way to have a child process on windows ignore SIGINT send to the parent? Cheers and thanks, Brian

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Re: [Twisted-Python] Twisted webserver performance issues
by Tom Leys Nov. 8, 2009

Nov. 8, 2009

Neither of the below issues will be a problem Jean-Paul Logged in users have a cookie set (I imagine). by default Varnish will not present cached results to users with a cookie, nor will it cache their results for others to see. So the 10% of hits (totally my guess) that are for authenticated users will not be cached. However, some more static assets could be cached regardless of cookies if we so desire. James: Varnish has an option to serve an old result out of cache if the server is being non-responsive, it is a feature they call "Grace" -Tom Where this gets hard is that the front page looks different depending on whether the person requesting it is anonymous or authenticated. If they're anonymous, various links are not presented. If they're authenticated, they get the extra links and their username is part of the page. Jean-Paul ------------------------------ When I last looked into the performance issues, I found that sometimes trac appears to block for long periods of time without releasing the GIL. That seems to be the core of the performance issues, currently. When it's responding normally, it's perfectly snappy. But, sometimes, it blocks for 10sec at a time. My next attempt to improve performance was going to be to run trac in subprocesses instead of threads. That would hopefully substantially fix the delay problem. James

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[Twisted-Python] Weekly Bug Summary
by exarkun＠twistedmatrix.com Nov. 8, 2009

Nov. 8, 2009

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Re: [Twisted-Python] Twisted webserver performance issues (was volunteer...)
by exarkun＠twistedmatrix.com Nov. 8, 2009

Nov. 8, 2009

On 10:41 pm, leyssw(a)ihug.co.nz wrote: > >Isn't the simplest option to place a decent reverse proxy between the >webserver and our clients? Possibly so! I gave this a half-hearted attempted a few weeks ago but quickly gave up. If someone who is familiar with configuring such a proxy would like to help out, perhaps we can get something useful up and running. > >For example, varnish will cache and proxy simple GETs, so simple views >of the front page and docs (which I imagine is a large chunk of the >traffic) will be offloaded from the webserver: >http://varnish.projects.linpro.no/wiki/VarnishFeatures > >Also, is the current installation (Db, apache + trac) all on one >machine or are the DB and the webserver split already? They're all on one machine. Changing this is an expensive proposition with a hard to predict payoff, so it's rather low on the list of ideas to try. >These would be easy ways to throw more hardware at the problem. > >What is the current web-server configuration? Can you be more specific about which configuration you're interested in? >Can you share traffic stats for the top 20 pages, so we get an idea of >where the load is? Yep. Here are counts for the last few days. Rank, request count, URL. 1) 22058 /trac/ 2) 8742 /trac/attachment/wiki/TSF/SponsorLogos/seomoves.png?format=raw 3) 8646 /trac/attachment/wiki/TSF/SponsorLogos/zenoss.2.png?format=raw 4) 8550 /trac/attachment/wiki/TSF/SponsorLogos/Appropriate- Solutions-Inc.gif?format=raw 5) 8499 /trac/attachment/wiki/TSF/SponsorLogos/securitymetrics.png?format=raw 6) 3075 /trac/wiki/Documentation 7) 2615 /trac/timeline?changeset=on&max=100&daysback=10&format=rss 8) 2448 /trac/wiki/Downloads 9) 1788 /trac/wiki/FrequentlyAskedQuestions 10) 1356 /trac/wiki 11) 1019 /trac/wiki/TwistedProject 12) 966 /trac/wiki/TracGuide 13) 828 /trac/wiki/TwistedWeb 14) 814 /trac/robots.txt 15) 781 /trac/search 16) 710 /trac/wiki/TwistedProjects 17) 662 /trac/wiki/WikiStart?format=txt 18) 605 /trac/wiki/TwistedAdvantage 19) 595 /trac/report/9 20) 590 /trac/timeline?milestone=on&ticket=on&changeset=on&wiki=on&max=50&daysback=90&format=rss Looking at this, I'm reminded that we should try moving the sponsor logos to somewhere else Unfortunately one thing we don't know is the relative cost of serving each of these URLs. The sponsor logos, while accounting for a significant number requests, may actually be a very small contribution to overall load. Anyhow, thanks! Jean-Paul

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[Twisted-Python] Twisted webserver performance issues (was volunteer...)
by Tom Leys Nov. 7, 2009

Nov. 7, 2009

Isn't the simplest option to place a decent reverse proxy between the webserver and our clients? For example, varnish will cache and proxy simple GETs, so simple views of the front page and docs (which I imagine is a large chunk of the traffic) will be offloaded from the webserver: http://varnish.projects.linpro.no/wiki/VarnishFeatures Also, is the current installation (Db, apache + trac) all on one machine or are the DB and the webserver split already? These would be easy ways to throw more hardware at the problem. What is the current web-server configuration? Can you share traffic stats for the top 20 pages, so we get an idea of where the load is? -Tom > From: "ssteinerX(a)gmail.com" <ssteinerx(a)gmail.com> > Subject: Re: [Twisted-Python] Volunteer for twisted code Reviews and > Commits > To: Twisted general discussion <twisted-python(a)twistedmatrix.com> > Message-ID: <C38535FC-8267-4162-B67C-1F27822CBC8D(a)gmail.com> > Content-Type: text/plain; charset=us-ascii; format=flowed; delsp=yes > > > On Nov 7, 2009, at 8:51 AM, David Lyon wrote: > > >> Hi Jean-Paul, >> >> On Sat, 07 Nov 2009 13:32:28 -0000, exarkun(a)twistedmatrix.com wrote: >> >> >>> A server farm doesn't buy us anything, as trac can't be scaled up >>> across >>> multiple hosts (or even multiple CPUs on a single host). >>> >> I'm surprised to hear that. >> >> Usually replication of servers for read requests works well >> with dns sharing. >> >> Does Trac not run a database? that can go on another machine and >> lighten the load. >> >> Anyway, it's your call. Keep up the good work. >> > > I think the best option may just be to collect machine, database, and > usage stats and ask the trac guys for help. > > S > > > > > ------------------------------ > > _______________________________________________ > Twisted-Python mailing list > Twisted-Python(a)twistedmatrix.com > http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python > > > End of Twisted-Python Digest, Vol 68, Issue 12 > ********************************************** > >

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[Twisted-Python] twisted server for recording streaming audio
by Josef Novak Nov. 6, 2009

Nov. 6, 2009

Hi, I'm interested in using twisted to build a server for recording streaming audio. I've spent some time googling and looking through the archives but haven't been able to find much in the way of examples for this sort of usage. To be clear, I'm not trying to stream media from the server to the client, but want to stream the audio from (potentially multiple) clients to the server, where it will be recorded and possibly later annotated for reference. The closest possible example of this sort of usage scenario that I was able to find was shtoom, but I wasn't able to get very far with that, as the source does not seem to be available, despite the site still being up (perhaps I just couldn't find it ). Does anyone know of any working examples of such usage that might be easily adapted. I'm really only looking for the simplest possible base example that would allow me to connect one or more clients over localhost and stream the audio to the server. On the other hand, perhaps it is better to just go with the bundled SocketServer module to start with? Cheers

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[Twisted-Python] Gridspy - a new project using Twisted
by Tom Leys Nov. 6, 2009

Nov. 6, 2009

Hi Everyone I would like to introduce my project for the http://twistedmatrix.com/trac/wiki/ProjectsUsingTwisted page. We use twisted as the central server that talks to many power measurement sensors in the field. " Gridspy provides you with an interactive view of resource usage in your building. It gives you hard data on your consumption patterns and helps you to make informed decisions. ... The Gridspy allows you to access and monitor your consumption patterns in real-time using a standard web browser on your PC, laptop or mobile phone. The data is presented in high resolution and updated each second as you watch. The moment a light is turned on in your house, you can see the change on your Gridspy dashboard from across the room or across the planet. " Our homepage is here http://www.gridspy.co.nz/ a running demo is here http://your.gridspy.co.nz/powertech And you can read more about the role of our twisted backend here: http://blog.gridspy.co.nz/2009/10/realtime-data-from-sensors-to-browsers.ht… " ... The nexus then collects those sensor samples from the nearby Gridspies, bundles it up with its own data and uploads it to our central servers. To collect the data we use a custom application written using the excellent Twisted framework <http://twistedmatrix.com/>. Every single reading gets instant attention: it is evaluated for real-time events, queued to be stored in the database and finally forwarded to watching dashboard users. Processing the data stream live on the server opens up many exciting possible features that I look forward to discussing in future blog posts. By the time that the sample reaches the server, it is about 0.2 seconds old. ... " It has been a great framework to work with. My sincere thanks goes to everyone who has ever contributed to this project. Job very well done! -Tom

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[Twisted-Python] Logging to both console and file (using twisted logging API)?
by naman jain Nov. 6, 2009

Nov. 6, 2009

Hi, I wanted to log in a file and keep the console also going with it. I am using log.startLogging(open(logname, 'w')) whatever documentation I could find about this API, it suggested me to pass setStdout=False(in order to keep stdout away from putting into log) somewhere in the startlogging function. Something like this I tried: log.startLogging(sys.stdout,setStdout=False) Doesnt help in solving the problem of getting both things: Requirement: log.msg("messageforlog") -> goes to log print "message for console" -> goes to console Could anyone give some ideas on this? Regards Naman

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[Twisted-Python] help needed with flow-control for push protocol
by Pietro Niccoli Nov. 5, 2009

Nov. 5, 2009

Hi, I need assistance figuring out how to create a push protocol that implements flow control. To keep things simple, I'm trying to build a push-based echo server. It should (1) accept incoming tcp connections (2) on each connection, all data rec'd should be echo'd unchanged. (3) should the output transport request that transmission be "paused," the input transport (in this case, the same socket) should be similarly blocked. This would seem to be a simple problem. I think my "PushEcho" class should implement both IConsumer and IProducer interfaces; As a consumer, its dataRecieved method would cause it to act like a producer and call the transport's dataReceived method. Similarly, as a producer, it's pause, and resume methods would be called, and they would (as a consumer) just call the same functions in the transport. However, I can't get the plumbing right. Can someone help by providing pointers or some sample code? Thanks.

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[Twisted-Python] Twisted and wxPython
by Jon Mills Nov. 5, 2009

Nov. 5, 2009

Can anybody point me towards a nice up-to-date example of the use of Twisted with wxPython? I assume (hope) there's some way to bind the wx event loop into Twisted's Reactor? Or do they need to run in separate threads/processes? Thanks in advance, Jon Mills

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[Twisted-Python] Need replacement for subprocess.call within a pyAMF method - any suggestions?
by Read Roberts Nov. 5, 2009

Nov. 5, 2009

I am trying to use the twisted reactor as a basis for a Python server for a Flex app, using pyAMF. My problem is that one of the server methods requires me to run a series of command-line tools to complete parsing data from a file into an XML object, with lots of Python processing on the results of one command-line tool to provide the input to the next one. I have been using subprocess.call to invoke the command-line tools, but these intermittently - and frequently - fail with an error "IOError: [Errno 4] Interrupted system call". I do know that this was supposed to be fixed in twisted for Python 2.6, but it doesn't seem to be. I have python 2.6.3 under Mac OSX 10.5.8, and twisted 8.2.0. Is there a work-around for this problem, or a better way to do this with twisted? I do know that I can make a command-line call with reactor.callLater, and that I can return a deferred from my server method, but I don't see how to easily accomplish the chain of calls that I need, short of breaking up my serverMethod1 into the several sequential parts, and calling each from the result handler of the previous one. I'd rather not go that route, as the logic of which command-line call gets made when is actually quite complicated. What I have now looks like (enormously simplified): class MyPythonServer: def serverMethod1(self, dummyPost, inputFilePath): # Open inputFilePath, do stuff, save results to file2 subprocess.call(["command1", "file2", "file3"]) # Open file3, do stuff to the data, save results to file4 subprocess.call(["command2", "file4", "file5"]) # Open file5, convert data to a large string containing XML. return xmlString - Read Roberts

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Re: [Twisted-Python] Trial: testing multiple test modules in one go?
by Paul Goins Nov. 5, 2009

Nov. 5, 2009

Tim Allen wrote: > Paul Goins <general(a)vultaire.net> wrote: >>> Does "trial tests" not work? (you probably need a tests/__init__.py) >> Nope: >> >> $ trial tests >> >> >> ------------------------------------------------------------------------------- >> >> PASSED >> >> Nothing executes if I run it that way. And I do have the >> tests/__init__.py. It's totally empty, in case it matters. > > Just to be sure, your test modules are named "tests/test_foo.py", > "tests/test_bar.py" and so forth? That appears to be it. I thought it was just the function names that needed to follow the test_<foo> pattern. I don't seem to see this documented, either... Guess I'll add a comment to #2443. Thanks for the help!

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[Twisted-Python] Trial: testing multiple test modules in one go?
by Paul Goins Nov. 5, 2009

Nov. 5, 2009

My project has 160 or so test functions spread across 29 test modules. The layout is something like this: project_root/ <project>/ <module>.py <module>.py ... tests/ <test_module>.py <test_module>.py ... unit_tests.py Running tests one-by-one ("trial tests.<test_module>") works perfectly. However, I want to test them all in one go, and can't find a "proper" way to do it. Currently to test it, I have a module, tests.unit_tests, which imports all the tests from all other modules in the tests namespace via: from tests.<test_module_1> import * from tests.<test_module_2> import * ... However, this is less than ideal, since if someone makes a unit test class with the same name as one in another module, they overlap and one ends up untested. (We just got blindsided by this to some degree, hence the e-mail.) I'll probably end up just attaching the test module's name as a prefix to each test class, but I wanted to ask, is there a better, "proper" way of doing this? Thanks. - Paul Goins

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[Twisted-Python] ProducerConsumerProxy problem
by Pietro Niccoli Nov. 4, 2009

Nov. 4, 2009

Hi, I'm trying to write a simple echo server but with control flow. The program should send back all the data it receives from a client, but if one of the clients that are connected stop accepting the data that is sent back, my program should tell it to stop sending data too, for preventing to run out of memory. I've seen that twisted offers an iConsumer and iProducer classes, so my class should implement both of them. I know how to write the producer part, but I still having trouble in telling twisted that my class is a consumer for the transport. This is because usually in a program, whenever there is data available, the dataRecived function of the program is called, passing the data to it, so I don't know who I can pass as a producer for my echo class. I know that there's a class called BasicProducerConsumerProxy in pcp that seems to do my job, but I'm stuck in making it understand that "transport" is both a consumer and a producer. The code should be something like this: Echo = protocols.pcp.BasicProducerConsumerProxy(self.transport) #register transport as a consumer Echo.registerProducer(self.transport, True) #register transport as a producer But it doesn't work. Can you help me? An example will be greatly appreciated. Thanks. Pietro

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[Twisted-Python] Unpedictable behaviour of transport.write call: Problem with return the control to reactor
by naman jain Nov. 4, 2009

Nov. 4, 2009

Hi, I was trying this out: Server code: def dataReceived(self, data): if (args["cmd"] == "CHECK_IN"): foo = subprocess.Popen('python master.py',shell = True) *# this ACK notifies the client to close the connection* self.transport.write( self.create_message("CHECK_IN","ACK") ) I use the subprocess call , as I want to avoid threads here, and independently launch my master.py without blocking this code. I dont aim to have any interaction with the master.py once it is launched Now, I see unpredictable behaviour here.. I have been trying many times, but the subprocess call does not happen everytime ! The connection is closed by the client without the master getting launched in some cases. How does the transport.write behave in such cases.. Do you people see a structural problem here.. Or adding some small delay of 2 sec before transport.write might help? Regards Naman

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[Twisted-Python] Connect to an IRC server, modules.
by Alberto Piu Nov. 4, 2009

Nov. 4, 2009

Greetings, first of all, I apologize for bad english. I am new with Twisted, and although it seems very powerful, I'm having some problems in using it. I'm trying to create an IRC bot, which basically does nothing. My idea is to write a skeleton that's improved by modules, which do different things in an IRC channel. When some events happen some modules become active, so that they can send messages, or notices, or private messages, and all what an IRC bot can do; so, every module has to have complete access to the methods of the bot class, but in the same time I need to keep the two things separated, to improve modularity. I used an example, called LogBot example. I have a .py file (I'll call it "mainfile), in which the LogBot class is located, where the reactor is set up etc, then I have a dir called modules, where modules are. - mainfile.py - modules - modulea - modulea.py - moduleb - moduleb.py (I omitted __init__.py files). Now the question is: how I can make accessible all the methods of the LogBot class from EVERY .py inside the modules directory? I tried to do the following: In the mainfile, inside the LogBot class, I have def joined(self, channel): """This will get called when the bot joins the channel.""" self.logger.log("[I have joined %s]" % channel) This method is called when the bot joins the channel "channel". Know, if I want to use modulea to greet user "x" when I enter the channel, I would write: def joined(self, channel): """This will get called when the bot joins the channel.""" self.logger.log("[I have joined %s]" % channel) modulea.greet("x", "Hi, user x") where greet is a function inside the module modulea (imported somewhere in my mainfile). Anyway, modulea is defined as following: def greet(who, message): ## But here, how can the function know the method to use? The solution can be... ##In mainfile.py def joined(self, channel): """This will get called when the bot joins the channel.""" self.logger.log("[I have joined %s]" % channel) modulea.greet(self, "x", "Hi, user x") ##In module a: def greet(bot, who, message): bot.msg(who, message) But this does not work. I tried to explain as better as I could. If you can, please use examples and speak easy (can't understand very well). Hope you can help me! Thank you, in advance. --Alberto Piu

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[Twisted-Python] twisted.internet.error.ProcessTerminated, exit code 1?
by Galina Kistanova Nov. 3, 2009

Nov. 3, 2009

Hello all, I ran into issue with Twisted, could anybody help me? I have Twisted 8.2.0 on Ubuntu 9.04. I run tests for Buildbot 0.7.11p3 and one of the tests completed with the next error: [ERROR]: buildbot.test.test_locks.Locks.testLock3 Traceback (most recent call last): Failure: twisted.internet.error.ProcessTerminated: A process has ended with a probable error condition: process ended with exit code 1. Cannot find any information what could cause this. What “exit code 1 “ means? I tried to stop MsAfee, but this did not help. Thanks Gal

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Re: [Twisted-Python] The case of the missing Traceback
by Terry Jones Nov. 3, 2009

Nov. 3, 2009

>>>>> "Dan" == Dan <tw.1(a)pyxos.com> writes: Dan> I was playing around with Twisted today and ran into a problem where Dan> Tracebacks aren't emitted on stderr after a deferred callback from a Dan> process called launched by reactor.spawnProcess. The simplified test Dan> case is below. I put "x = y" in the callback function to generate an Dan> exception, y doesn't exist. Uncomment "x = z" right before the Dan> callback and it produces the traceback on stderr just fine. Hi Dan The callback function raises an exception, which Twisted converts to failure and stores in the deferred. But seeing as there are no errback functions in the deferred *and you leave the reactor running*, the failure just sits there (just as it should). If you do a 'from twisted.python import log' and Change the addCallback line in test() to look like this d.addCallback(response).addErrback(log.err) You'll see the expected NameError just fine. Terry

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