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simple twisted server (twistd .tap)with a pexpect instance error

Answer 1

+3 A:

You're spawning a child process before daemonizing. After daemonizing that child is now a child of init, and not a child of your daemon.

You need to subclass from twisted.application.service import Service and spawn the child process in startService, which will be called after daemonizing.

Á La: http://stackoverflow.com/questions/1470850/twisted-network-client-with-multiprocessing-workers

Edit: implementation

I can't test this entirely as I don't have your amulecmd, but try something more like this:

#!/usr/bin/env python
# vim:ai:et:ts=2:sw=2:bg=dark
from twisted.internet import protocol
from twisted.protocols.basic import LineOnlyReceiver
from twisted.application import service


from xml.etree import ElementTree as ET

from aMuleClass import amulecmd

class DialogueProtocol(LineOnlyReceiver):
  def connectionMade(self):
    print "Connected: %s" % self.transport.getPeer().host
  def lineReceived(self, line):
    parsed= ET.XML(line)
    if parsed.attrib['type'] == 'request':
      if parsed.attrib['prompt'] == 'results':
        self.transport.write(self.factory.mule.results())
      elif parsed.attrib['prompt'] == 'downloads':
        self.transport.write(self.factory.mule.downloads())
      else:
        print "Invalid request: %s\n" % line
    else:
      query= parsed.attrib['value']
      if parsed.attrib['type'] == 'search':
        print "must search for %s" % query
        self.factory.mule.search(query)
      elif parsed.attrib['type'] == 'cancel':
        print "must cancel %s" % query
        self.factory.mule.command("cancel %s" % query)
      elif parsed.attrib['type'] == 'download':
        print "must download %s" % query
        self.factory.mule.command("download %s" % query)

class MyService(service.Service):
  def __init__(self,port=14000):
    self.port = port
  def startService(self):
    self.factory = protocol.Factory()
    self.factory.protocol = DialogueProtocol
    from twisted.internet import reactor
    reactor.callWhenRunning(self.startListening)
  def startListening(self):
    self.factory.mule = amulecmd()
    from twisted.internet import reactor
    self.listener = reactor.listenTCP(self.port,self.factory)
    print "Started listening"
  def stopService(self):
    self.listener.stopListening()

if __name__ == '__main__':
  pass
else:
  application = service.Application("aMuleSocket")
  services = service.IServiceCollection(application)
  MyService().setServiceParent(services)

MattH 2010-02-17 19:46:59

This is great!! i'm really "glad" someone has had the same problem as me and has managed to resolve it!!The amulecmd class has to be spawned is the ServerFactory subclass, so that it can be accessible to any connection, how can i do this? i correctly implemented MultiprocessingService but if i spawn the process there i wouldn't know how to access it. ideas? Thanks for the help

PirosB3 2010-02-17 20:35:37

If your `amulecmd` returns an object with a method that lets you shutdown the subprocess gracefully, then you can call it in the `stopService` method.

MattH 2010-02-17 22:58:51

Thanks again Matt...This works perfectly!!! :D

PirosB3 2010-02-24 14:19:20

You're welcome. Nice to be able to help someone with Twisted instead of crashing against their misconceptions about it!

MattH 2010-02-24 14:38:03

Answer 2

A:

Hey! Thanks for sharing. I am doing more or less the same at the moment, that means have a twisted server talking xml to a client and running this as a daemon. In my case the client will be a kind of an external automation system.

daccle 2010-03-26 10:45:15

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simple twisted server (twistd .tap)with a pexpect instance error

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