Mailman 3 January 2005 - Twisted

[Twisted-Python] Question on new code development
by Bill Krueger 21 Jan '05

21 Jan '05

I am in the process of building an interactive game server and client with the client code written in Java and I have a couple of questions. I am hoping to be up and running with a prototype in the next month. My plans incluse the use of Twisted framework as I'm very comfortable in Python as well as Java. My first question is, should I be looking at the new Twisted 2.0 for development or stick with 1.3 and plan on upgrading to 2.0 later. Secondly, would using and/or building upon TwistedJava for the communications between the Java clients and my Twisted server code be a good direction to take? Thanks, -- Bill Krueger <bill.krueger(a)comcast.net>

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[Twisted-Python] Twisted PB and Zope
by Uwe C. Schroeder 21 Jan '05

21 Jan '05

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi everyone, is there a way to use Zope as a client to Twisted PB ? Background is that I have a nicely working application using Twisted. The GUI client is wxPython based and talks to the server part using PB. Now I'd like to add a webinterface that would ideally use PB to to talk to my application server part and retrieve some of the information. Is that possible at all? Any pointers? Thanks UC - -- Open Source Solutions 4U, LLC 2570 Fleetwood Drive Phone: +1 650 872 2425 San Bruno, CA 94066 Cell: +1 650 302 2405 United States Fax: +1 650 872 2417 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.3 (GNU/Linux) iD8DBQFB8TJRjqGXBvRToM4RApwEAKCpLF12s56kJWU8SJ/PX3TaFBOS3QCfROth uCwYXHV/JOEwl/kKNnxHZjU= =1FBI -----END PGP SIGNATURE-----

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[Twisted-Python] succeedForOneOf
by Justin Johnson 20 Jan '05

20 Jan '05

I wrote succeedForOneOf to help when I want to loop through a list and call a function with the item from the list as the first argument to the function, and stop when one of the function calls succeeds. The use case I need it for is, connecting to multiple servers looking for a particular thing, and stopping when I find it. In my testing in the attached file, succeedForOneOf does what I would expect. However, when I tried this in my application, and func involved connecting to servers via PB and calling a remote method, it started up a ton of 'PBClientFactory's until the win32eventreactor spun wildly out of control because I exceeded the 64 object limitation. This of course also caused the server I was connecting to to spin wildly out of control as well, sucking up all of the CPU. My question isn't related to the win32event reactor problem. I just don't understand why my implementation of succeedForOneOf would fail in this manner. Does anyone see a problem with the code? Has someone else written code to accomplish this in a different way? -Justin

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[Twisted-Python] Inheriting from both pb.Cacheable and pb.RemoteCache?
by Steve Freitas 19 Jan '05

19 Jan '05

Hi! In the PB howto, it mentions that it's typical and fine to get bidirectional synchronization between objects by inheriting from both pb.Copyable and pb.RemoteCopy. Is the case the same when it comes to Cacheable? I want a client to log in and grab attributes of objects as needed from the server, and any changes made to the objects on either side ought to be replicated on the other end. This looks like the way to accomplish that, but I want to verify my suspicion before Twisted bends my brain again. :-) Thanks! Steve

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[Twisted-Python] "Directory triggers" with kqueue using Twisted? (on MacOS X / FreeBSD)
by Wolfgang Keller 18 Jan '05

18 Jan '05

Hello, recently I read something about the "kqueue" event notification mechanism built into FreeBSD and that it would allow to receive notification when filesystem contents change. Would this mechanism allow to implement a similar function as database triggers for a filesystem, i.e. write a script that does something with files that are added to, modified in or deleted from a certain directory without having to poll the filesystem all the time? Folder actions allow such things on MacOS X, but Applescript is slow and I would prefer Python anyway. ;-) If so, is there a way to write such scripts in Python using Twisted? TIA, Best regards Wolfgang Keller

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[Twisted-Python] Re:
by Stephen 14 Jan '05

14 Jan '05

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[Twisted-Python] ProcessProtocol randomly not returning all of stdout
by Justin Johnson 13 Jan '05

13 Jan '05

I recently started running into a problem where my process protocol isn't extracting stdout accurately in all cases. I have a method on a service that loops through a list and runs a command, passing in each item on the list one at a time. Out of ~50 items in the list, and thus ~50 invocations of the command, one or two will fail to extract all of stdout from the command. Instead the first character of stdout is extracted and that is it. The process protocol I'm using is below. Does anyone see anything wrong with the code? I am using the win32event reactor and Twisted 1.3.0. from twisted.internet import reactor from twisted.internet import protocol, error, defer from twisted.python import log from ratcontrol import errors, config import os, sys class BasicProcessProtocol(protocol.ProcessProtocol): def __init__(self): self.deferred = defer.Deferred() self.stdout = "" self.stderr = "" self.status = 0 def connectionMade(self): self.transport.closeStdin() def outReceived(self, data): self.stdout += data def errReceived(self, data): self.stderr += data def processEnded(self, reason): if reason.check(error.ProcessDone): self.status = 0 # pass the items we want down the callback chain self.deferred.callback((self.status, self.stdout, self.stderr)) else: self.status = 1 theError = errors.CmdError(self.cmd, self.status, self.stdout, self.stderr) log.msg(theError) self.deferred.errback(theError) def openProcess(cmd_and_args): cmd = cmd_and_args[0] args = cmd_and_args[1:] # Spawn the process using the reactor so we don't block proto = BasicProcessProtocol() proto.cmd = cmd_and_args reactor.spawnProcess(proto, cmd, cmd_and_args, env=os.environ) return proto.deferred

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[Twisted-Python] Re: [Twisted-commits] r12864 - Temporarily workaround z.i bug.
by Andrew Bennetts 12 Jan '05

12 Jan '05

On Wed, Jan 12, 2005 at 02:23:38PM -0700, James Knight wrote: [...] > + # Until this is fixed, make *sure* fixClassImplements was > + # called before looking anything up in AdapterRegistry. > + # http://collector.zope.org/Zope3-dev/349 > + if hasattr(ob, '__class__'): > + fixClassImplements(ob.__class__) > + fixClassImplements This last line looks a bit dubious :) -Andrew.

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[Twisted-Python] TCP test harness
by Braun Brelin 11 Jan '05

11 Jan '05

Has anyone written a TCP test harness in Twisted/Python? Someone has asked me to write one, but I'm fairly new to twisted (less new to Python) and it seems that it would be silly for me to write something if someone else has already written and/or posted one. Basically, I'm looking for a TCP test harness that will support up to a thousand concurrent TCP connections at a time sending data to a remote device. Thanks, Braun Brelin

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[Twisted-Python] Interactive Twisted client (newbie question?)
by Jon Blower 10 Jan '05

10 Jan '05

Hi all, I'm new to Twisted, and I'm trying to create an implementation of a client program that communicates over a network with a server using a protocol called Styx. (In case you're interested, Styx is a protocol for distributed systems, as used by the Inferno operating system: http://www.vitanuova.com/inferno/papers/styx.html.) In short, Styx is a pretty simple call-response type of protocol, in which the client sends a T-message and waits for the corresponding R-message from the server. There is a one-to-one correspondence between T- and R-messages. I understand that Twisted is an event-driven framework and I have written a basic client program. My initial attempt has involved creating a StyxProtocol class that inherits from protocol.Protocol, in which I override key methods such as dataReceived() and connectionMade(). Having created this protocol and told it how to respond to messages that arrive, I created a simple Factory class, then set the whole thing running with reactor.run(). It works fine, but it's not quite in the form I'd like. In my current attempt, what I've done is essentially to create a load of callbacks and "press GO". Once I've set the program running I can't interact with it until one of the methods calls reactor.stop(). What I'd like to be able to do is illustrated by the following pseudo-Python. This could be a script or could be typed into an interactive Python shell: conn = StyxConnection("myserver.remotehost.com", 6666) conn.connect() # Starts the reactor going and performs handshakes # The connection is now open and I can interact with it myRemoteFile = conn.openFile("/path/to/myfile") # Gets handle to file on remote server, by exchange of a few messages data = myRemoteFile.read() # Reads data from the remote file, again by exchange of some messages conn.close() # Closes the connection to the remote server and stops the reactor How can I do this with the Twisted framework? As far as I can tell, reactor.run() will not return until something calls reactor.stop(). I could achieve what I want using threads (I think), but I'd like to avoid this if possible. I'm sure I'm not the first to ask this sort of question, but I've looked through the docs and example code and haven't been able to track down an answer. I'd be very grateful for any pointers that anyone could offer. Regards, Jon -- -------------------------------------------------------------- Dr Jon Blower Tel: +44 118 378 5213 (direct line) Technical Director Tel: +44 118 378 8741 (ESSC) Reading e-Science Centre Fax: +44 118 378 6413 ESSC Email: jdb(a)mail.nerc-essc.ac.uk University of Reading 3 Earley Gate Reading RG6 6AL, UK -------------------------------------------------------------- ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.

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