Mailman 3 June 2011 - Twisted

[Twisted-Python] Handling application initialization synchronously
by David June 20, 2011

June 20, 2011

Hi, I was wondering what's the recommended way to initialize a "complex" twisted application. Typically, let's say I have an application which needs to create a couple of "heavy" objects, each of which may create mysql db/tables: class MyApplication(object): def __init__(self): # object1 and object2 may need to interact with MySQL, # and object2 assumes that object1 is completely initialized object1 = SomeClass1() object2 = SomeClass2() Writing … [View More]

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[Twisted-Python] Twisted training slides
by Orestis Markou June 20, 2011

June 20, 2011

Hi again, I'd greatly appreciate if someone could have a quick look through my slides: http://dl.dropbox.com/u/34284/twisted_training.pdf (64MB PDF) and comment on possible inaccuracies or flat-out wrong things. I have simplified some things in the beginning, but I expand later on. Many thanks, Orestis

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[Twisted-Python] Weekly Bug Summary
by exarkun＠twistedmatrix.com June 19, 2011

June 19, 2011

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[Twisted-Python] Real-world but self-contained example?
by Orestis Markou June 18, 2011

June 18, 2011

Hello, I'm trying to come up with a real-world example of performant twisted code to show as the conclusion of the europython training I'll be giving this Monday. After much help in the #twisted channel, I've written a simple "website monitoring service". I'm trying to keep everything as small and self-contained as possible. There are 3 files, one with a very simple http GET implementation, one with a 1000 sites (some might be NSFW-this is taken from the Alexa site rank) and a simple web … [View More]

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[Twisted-Python] Building API documentation
by Orestis Markou June 18, 2011

June 18, 2011

Apologies for the flood of messages - I'm getting anxious about this training ;) I'm looking for a way to build (or download) the API reference offline, so each trainee would have it locally for faster access. Looks like I should be using t.p._release.APIBuilder, but presumably there's an automated script to do all that (and change the included html docs to point there as well?). One of the aims of the training is to teach people to grok the docs (and the source), so we'll be diving into the … [View More]

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[Twisted-Python] Ideas for a Twisted Training
by Orestis Markou June 17, 2011

June 17, 2011

Hello, In a few days I'll be giving a 4h long training on Twisted in Europython 2011 in Firenze, Italy. I have a lot of material covering basic concepts, such as writing servers, writing clients, deferreds etc. I'm now looking for other areas of functionality I should show. I have a bit web, will do a bit of pb. Any other pointers? Also, if anyone else from the Twisted community is going to be there, let's have a drink. Disclaimer - I don't claim I'm a twisted expert. At first I hated … [View More]

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[Twisted-Python] Looking for Devs to answer noob questions on 6/22 & 6/23
by David Shein June 16, 2011

June 16, 2011

Hey Twisted Developers, I'm looking to get a half dozen devs who will commit to being on the Twisted IRC channel next Wed and Thurs during biz hours to answer noobish queries from CS faculty working in an OS environment for the first time. One group will be working on Twisted bug tickets. All the details are below. If you are interested please LMK on the list, or you can email me directly at dshein at rochester.rr.com. Dave Shein Rochester Institute of Technology Greetings: My name … [View More]is Dave Shein, and I'm an Adjunct Faculty at Rochester Institute of Technology. Along with Chris Tyler of Seneca College, we are hosting a week long POSSE boot-camp at the RIT campus from June 20th -24th. POSSE, sponsored by Red Hat, is a week long educational hand-on seminar in open source process, collaboration, and education. The central purpose of POSSE is to increase awareness and opportunities for Open Source participation in the university setting. All POSSE participants are university staff or faculty who will take what they learn in POSSE and use that knowledge in CS and related curricula, to spread the word about open source collaboration, and to provide increased educational opportunities for CS related students. Our first two days are spent acclimating our participants to tools and resources of the open source community, but on the third and fourth day of POSSE we will have our participants do a code-sprint. We are looking for opportunities in existing open source projects which have a quick learning curve and setup time for folks with a CS background but who in most cases will not have a great depth of experience working in open source languages. We are particularly interested in having our participants hack on Fedora based projects. The students will have a Fedora F14 & F15/Linux work environment setup as part of their initial orientation, and we are looking for projects that will not have lengthy setup beyond the participants' initial setup. We obtained information about your open source project through OpenHatch, and would like to know if your project would have elements that would be amenable to our sprint. There will be approximately fifteen to twenty participants working on the sprint in teams of 3 to 5 people each, of whom most are coders. IN ADDITION we are also looking for a project participation opportunity for 3 to 4 non- coders, possibly in the form of testing, copywriting, or editing work. Ideally we would also like to coordinate with a point-person in your organization during the period of the sprint, a person to whom participants could direct questions, perhaps via IRC in real time. If this is of interest to you please contact me at your earliest convenience. I hope that we can work together soon. David Malcom Shein Rochester Institute of Technology IRC# ProfSheinRIT on freenode [View Less]

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[Twisted-Python] Example of re-usable ClientFactories?
by Orestis Markou June 15, 2011

June 15, 2011

Hello, I've gotten to the point in my tutorial that I'm giving out examples of writing clients. Example: class HTTPGETProtocol(protocol.Protocol): def connectionMade(self): self.buffer = [] self.transport.write('GET %s HTTP/1.0\r\n' % self.factory.path) self.transport.write('User-Agent: europython/2011\r\n') self.transport.write('\r\n') def dataReceived(self, data): self.buffer.append(data) def connectionLost(self, reason): self.… [View More]

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[Twisted-Python] Specifying the local port for a twisted.names DNS query or resolver
by Anton Gyllenberg June 15, 2011

June 15, 2011

I have external requirements that force me to issue DNS queries from a specific local port range. I'm looking for a way to use the twisted.names resolver but I need to specify a local port for a query or set the local port range for all queries. I appreciate that the local port randomization is there for good security reasons, but for my application I do not care. I would be grateful for any tips or guidelines on how to achieve this. For some ancient Twisted version I got it working by monkey … [View More]

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[Twisted-Python] Information on new endpoints API?
by Orestis Markou June 15, 2011

June 15, 2011

Hello, I'm curious about the endpoints API that appeared. I've read the documentation, and I think I understand what it does, but I'm curious to see what parts of twisted it replaces. A lot of the documentation on-site is not updated (eg the finger tutorial) and it's not very clear whether one should use reactor.listenTCP, TCPServer or the new API. I will be giving a training on Twisted in a few days during the EuroPython conference (actually, more of an assisted tutorial than a training) and … [View More]

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[Twisted-Python] Weekly Bug Summary
by exarkun＠twistedmatrix.com June 12, 2011

June 12, 2011

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[Twisted-Python] Weekly Bug Summary
by exarkun＠twistedmatrix.com June 5, 2011

June 5, 2011

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[Twisted-Python] Is this possible to catch this error? (returned by protocols/memcached.py)
by Attila Nagy June 3, 2011

June 3, 2011

Hi, Here's a sample application, which gets a key from memcached: from twisted.internet import reactor, protocol, defer from twisted.application import internet, service from twisted.protocols.memcache import MemCacheProtocol, DEFAULT_PORT mc = None class MemCacheFactory(protocol.ReconnectingClientFactory): protocol = MemCacheProtocol maxDelay = 5 # wait no more than 5 seconds to retry def buildProtocol(self, addr): p = self.protocol(self) p.factory = self … [View More] p.persistentTimeOut = p.timeOut = 5 global mc mc = p return p def memc(): factory = MemCacheFactory() reactor.connectTCP('localhost', 11211, factory) reactor.callLater(1,query) @defer.inlineCallbacks def query(): res = yield mc.get('test') print "XXX",res application = service.Application('memc') serviceCollection = service.IServiceCollection(application) reactor.callLater(0,memc) If memcached is running on localhost:11211, it writes the "test" key's value: $ twistd -noy memct.py 2011-06-03 14:48:27+0200 [-] Log opened. 2011-06-03 14:48:27+0200 [-] twistd 10.1.0 (/usr/local/bin/python2.7 2.7.1) starting up. 2011-06-03 14:48:27+0200 [-] reactor class: twisted.internet.selectreactor.SelectReactor. 2011-06-03 14:48:27+0200 [-] Starting factory <__builtin__.MemCacheFactory instance at 0x802a38710> 2011-06-03 14:48:28+0200 [MemCacheProtocol,client] XXX (0, None) Now I want to test the code for timeouts, where the TCP connection to memcached is open, but there is no answer. So instead of memcached, I start a netcat on port 11211: $ nc -l 11211 And start the above program. Now I get: $ twistd -noy memct.py 2011-06-03 14:50:08+0200 [-] Log opened. 2011-06-03 14:50:08+0200 [-] twistd 10.1.0 (/usr/local/bin/python2.7 2.7.1) starting up. 2011-06-03 14:50:08+0200 [-] reactor class: twisted.internet.selectreactor.SelectReactor. 2011-06-03 14:50:08+0200 [-] Starting factory <__builtin__.MemCacheFactory instance at 0x802a38710> 2011-06-03 14:50:14+0200 [-] Unhandled error in Deferred: 2011-06-03 14:50:14+0200 [-] Unhandled Error Traceback (most recent call last): Failure: twisted.internet.defer.TimeoutError: Connection timeout 2011-06-03 14:50:14+0200 [MemCacheProtocol,client] <twisted.internet.tcp.Connector instance at 0x804027dd0> will retry in 2 seconds 2011-06-03 14:50:14+0200 [MemCacheProtocol,client] Stopping factory <__builtin__.MemCacheFactory instance at 0x802a38710> As you can see, the connection is timed out, and protocols/memcached.py lost its connection. But how could I catch this around the "mc.get" call? I guess this error should raise an exception, so enclosing mc.get into a try-except would make possible to catch this. But currently this is not the case? How can this be solved? Thanks, [View Less]

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[Twisted-Python] Asynchronous code PEP
by Laurens Van Houtven June 3, 2011

June 3, 2011

Hi! I've just been in contact with Jim Fulton, who was previously mentioned in the context of developing this PEP, and he's okay with us taking over. IIUC the PEP involves a few things: 1. A sane reactor abstraction/interface (although they probably won't like pulling in z.i.I) in the standard library which everything should be able to implement -- essentially twisted.loop's interface. This probably includes a Protocol abstraction too 2. A simple, potentially insane … [View More]

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