Mailman 3 October 2009 - Twisted

[Twisted-Python] Phasing out old-style classes
by Kelly 27 Oct '09

27 Oct '09

On Thu Oct 8 20:08:12 EDT 2009, Glyph Lefkowitz <glyph at twistedmatrix.com> wrote: > On Thu, Oct 8, 2009 at 7:59 PM, Mark Visser <markv at lumierevfx.com> wrote: > > > I've been bitten a couple times by twisted's use of old-style classes. > > Now that Jython is finally off the 2.2 branch, is there any real reason > > to stay backwards compatible? > > > > Changing a class from old-style to new-style is an incompatible change. The > difficulty is that if existing libraries use a particular class and inherit > from it, changing the class to be new-style can have effects from changing > how their descriptors work to causing an exception when their module is > imported. > ... > > If old-style classes can be evolved into new-style classes while somehow > following this policy, that would be great. The problem is that providing > compatibility at this level is time-consuming and difficult. One problem in > particular is that we don't want to litter the codebase with lots of "Foo" > and "NewFoo" or "Foo2" sitting right next to it, so we would have to think > of new names for everything. > I have some POC code for this. It provides a simple toggle at the start of the application to select between old style (the default) and new style classes. After that, a DeprecationWarning is issued every time an old style class is defined. The only user visible change is that old style classes gain an empty old-style base class. The idea being the old-style/new-style migration could be managed using the usual twisted deprecation plan. Thoughts?

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[Twisted-Python] You guys are my heroes
by Don Schoeman 27 Oct '09

27 Oct '09

Just as the subject says... you guys (everyone involved with TM) are my heroes. Problem: I needed to develop a TCP server that could serve multiple GPS tracking devices over GPRS. These devices uses a multi-level (structures within structures) style binary protocol. I looked at various possible solutions which handled the complex asynchronous processing while I could concentrate on implementing the protocol. Time was of the essence (as it always is). Solution: I finally ran into Twisted Matrix and it immediately looked very promising. Only problem was that I didn't know Python at the time and looking at it for the first time I couldn't make heads or tails out of it. (I come from a Delphi background but knows a bit of C, PHP and Java as well). Anyway, after about a week of straining the old brain I not only managed to learn the basics of Python, but wrote my first concept server in TM and through it all learned to come to love both of these solutions very much! Final Verdict: About a month down the line my now completed server is running as smooth as butter handling an ever growing number of unit's just lovely. The data, once parsed is all pushed to a Apache/PHP based server via XML-RPC which in turn performs all the database related stuff. Thanks for all your hard work guys, it is noticed and deeply, deeply appreciated! Kind Regards, Don Schoeman

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[Twisted-Python] Can I post a consultant request here?
by Steve Steiner (listsin) 27 Oct '09

27 Oct '09

Hey! I apologize in advance if this type of request is not desired/allowed on this list. I'm looking for a very short-term mentoring/consulting contract to help me get an Ajax/Comet type of connection working between a web interface and a fairly long-running, server-side process. I want the web interface to reflect the server-side data as it becomes available. I'm sure someone on this list knows exactly how to hook the pieces together; I don't. It would be much more efficient to have someone who already knows help me hook it up instead of spending an unpredictable amount of time figuring it out myself. I'd also like to have, as a primary product of this project, a tutorial showing a real-world application of Twisted to handle a modern, real-world use-case with full, open, well documented source code. If you're interested, please contact me off-list at ssteinerx(a)gmail.com. Thanks, S

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[Twisted-Python] Handeling unresolved DNS queries?
by Jesper Taxbøl 26 Oct '09

26 Oct '09

Hi Guys, Im playing with a dns-cache script, that overrides DNS requests for certain IP addresses. I would like to add functionality, so unresolved requests are sent to a spicific IP. How do I go about doing that? Is there a negative answer in the (udp) DNS protocol or am I forced to use a timeout. Kind regards Tax import sys, os from socket import * from twisted.internet.protocol import Factory, Protocol from twisted.internet import reactor from twisted.names import dns, client, server import time LOGFILE = 'dnsfilter.log' def allowip(ip): return True class Log: """file like for writes with auto flush after each write to ensure that everything is logged, even during an unexpected exit.""" def __init__(self, f): self.f = f def write(self, s): self.f.write(s) self.f.flush() if __name__ == "__main__": dns_servers = [] f = open('/etc/resolv.conf', "r") while 1: line = f.readline() if not line: break if line[0]!='#': s, ns = line.strip().split(' ') if s == 'nameserver': dns_servers.append((ns,53)) #redirect outputs to a logfile sys.stdout = sys.stderr = Log(open(LOGFILE, 'a+')) print 'dnsfilter starting' print dns_servers #address that traffic is redirected to redirect = '10.0.64.1' greenlist= ['63.4.241.16', \ '216.13.188.67'] class DNSDatagramProtocolTest(dns.DNSDatagramProtocol): def writeMessage(self, message, address): log = '%s DNS request from: %s\n' % (time.strftime("%m/%d/%y - %H:%M:%S", time.localtime()) ,address[0]) for i in range(len(message.answers)): x = message.answers[i] print x.type if x.type==1 and x.payload: if not allowip(address[0]): to_adr = inet_ntoa(x.payload.address) if to_adr in greenlist: log += ' allowed to %s\n'%(to_adr) else: log += ' not allowed so %s becomes %s\n'%(to_adr, redirect) x.payload.address = inet_aton(redirect) else: log += ' to %s\n'%(inet_ntoa(x.payload.address)) print log self.transport.write(message.toStr(), address) resolver = client.Resolver(servers=dns_servers) f = server.DNSServerFactory(clients=[resolver]) p = DNSDatagramProtocolTest(f) reactor.listenUDP(53, p) reactor.run()

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[Twisted-Python] getting #2015 (Generic SASL library) moving again?
by Kevin Horn 26 Oct '09

26 Oct '09

I'd like to see this ticket get moving again. I've gone over what's been done so far (and put my comments in the ticket), and it looks like everything is at least mostly ready to be merged into the Twisted trunk. So what else needs to be done to get this to happen? I'm happy to try and get it done, but a little direction would be really handy. ;) Kevin Horn

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Re: [Twisted-Python] Gridspy - a new project using Twisted
by leyssw＠ihug.co.nz 26 Oct '09

26 Oct '09

Hi Maarten The Gridspy is a commercial product. At the moment we are manufacturing small runs of prototypes for development and testing, soon they will be available from our site on-line. We are making it "hacker friendly" and it has spare serial ports, digital and analogue inputs so electronics enthusiasts can make their own daughter boards. We hope it will then become a great way to take your inventions on-line. We consider our "secret sauce" to be the core hardware and the uplink to the web (including the twisted portion). Everything else on both ends will be open (still development efforts needed on SDK and documentation). You will be able to create an electronics gadget that sets the Gridspy / Nexus analogue and digital inputs and see those inputs changing in some script you wrote on the web via an RPC mechanism from our server. Right now our focus is on selling to commercial users here in Auckland, New Zealand (keep it local) to test the hardware. As production scales up, the pricing will become much more affordable for us normal people. Making our platform open and easy to work with is a cause close to my heart too. -Tom > Message: 3 > Date: Mon, 26 Oct 2009 10:14:30 +0200 > From: Maarten ter Huurne <maarten(a)treewalker.org> > Subject: Re: [Twisted-Python] Gridspy - a new project using Twisted > To: Twisted general discussion <twisted-python(a)twistedmatrix.com> > Message-ID: <200910260914.30601.maarten(a)treewalker.org> > Content-Type: Text/Plain; charset="iso-8859-15" > > On Monday 26 October 2009, Tom Leys wrote: > >> 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. > > How can other people get their own Gridspy? Do you plan to release it as a > do-it-yourself project or as a commercial product? > > Bye, > Maarten > > > > ------------------------------ >

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[Twisted-Python] Twisted Performance
by Daniel Griffin 25 Oct '09

25 Oct '09

Hi, I am new to twisted and have been having trouble finding out information about twisted's performance. I have a fairly simple setup where I need to open a bunch of TCP connections that last for varying amounts of time but dont do much. I have tried using threads(got GILed to death) and Processes(even worse). Now I am looking at either making a system to start the connection and send info to have the remote point "phone home" when its done, then closing the connection or using something like Twisted. my socket conversation: my app -> send a message that triggers an action on the other end other end -> recv's message does action(can take any amount of time) other end - > sends results back to my app Can twisted handle up to several hundred connections like this? Is there a better approach? Is there anything I should avoid? Thanks, Dan

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[Twisted-Python] Weekly Bug Summary
by exarkun＠twistedmatrix.com 25 Oct '09

25 Oct '09

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[Twisted-Python] How to chain deferred calls
by vitaly＠synapticvision.com 23 Oct '09

23 Oct '09

hi, how can I chain in defer methods that could raise exception while showing the exception that coming from method? I mean, if I'll do: return ( adc1().abc2().abc3().addErrback("Common2AllException") ) than "Common2AllException" will be raised if abc1() raise Exception, but I'd like to see the adc1() own exception (and not "Common2AllException") ? t = Test() def abc1(self): if t.test() is None: raise Exception("Error11") else: return 1 def abc2(self): if t.test() is None: raise Exception("Error12") else: return 1 def abc3(self): if t.test() is None: raise Exception("Error13") else: return 1 Appreciate the help.

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Re: [Twisted-Python] How to chain deferred calls
by Terry Jones 23 Oct '09

23 Oct '09

>>>>> "vitaly" == vitaly <vitaly(a)synapticvision.com> writes: vitaly> Thank you a lot for pointing me to the Twisted doc-s, but we're vitaly> discussing the following snippet: [snip] vitaly> and basically, I've expected in case of exception vitaly> self.handleFailure1() to be called, but I don't see it happen. The reason you're not seeing handleFailure1 being called is that the exception is not occurring in the context of deferred processing. You've got a regular Python function call, a regular exception is raised, etc. Twisted and its deferred do not / cannot alter that behavior. What they *can* do is handle exceptions and turn them into failures and route the failure to an errback chain *in the context of calling functions that have been added to a deferred*. Because your abc1 has not been added to any deferred's call/errback chain, none of that happens when your exception is raised. If your code looked like this (pseudocode), you would see the exception return ( self.abc1(). addErrback(self.handleFailure1). addCallback(self.abc2,args). addCallback(self.abc3). addErrback(self.handleFailure2) ) def abc1(self): d = defer.Deferred() d.addCallback(raiser) d.callback(1) return d def raiser(self, _): raise Exception("Error11") Because the thing that raises is being called by Twisted's deferred class, and its exception is caught and routed to d's errback chain and winds up in the handleFailure1 method. Does that make sense? Terry

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