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Simple UDP Multicast Client / Server using twisted (Python recipe) by Kyle Robertson
ActiveState Code (http://code.activestate.com/recipes/425975/)

Here is a simple example showing how to correctly use the UDP multicast functionality of twisted.

Python, 53 lines
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# Simple UDP Multicast Server example
# Kyle Robertson
# A Few Screws Loose, LLC
# http://www.afslgames.com
# ra1n@gmx.net
# MulticastServer.py

from twisted.internet.protocol import DatagramProtocol
from twisted.internet import reactor
from twisted.application.internet import MulticastServer

class MulticastServerUDP(DatagramProtocol):
    def startProtocol(self):
        print 'Started Listening'
        # Join a specific multicast group, which is the IP we will respond to
        self.transport.joinGroup('224.0.0.1')

    def datagramReceived(self, datagram, address):
        # The uniqueID check is to ensure we only service requests from ourselves
        if datagram == 'UniqueID':
            print "Server Received:" + repr(datagram)
            self.transport.write("data", address)

# Note that the join function is picky about having a unique object
# on which to call join.  To avoid using startProtocol, the following is
# sufficient:
#reactor.listenMulticast(8005, MulticastServerUDP()).join('224.0.0.1')

# Listen for multicast on 224.0.0.1:8005
reactor.listenMulticast(8005, MulticastServerUDP())
reactor.run()

#############################################################################

# Simple UDP Multicast Client example
# Kyle Robertson
# A Few Screws Loose, LLC
# http://www.afslgames.com
# ra1n@gmx.net
# MulticastClient.py

from twisted.internet.protocol import DatagramProtocol
from twisted.internet import reactor
from twisted.application.internet import MulticastServer

class MulticastClientUDP(DatagramProtocol):

    def datagramReceived(self, datagram, address):
            print "Received:" + repr(datagram)

# Send multicast on 224.0.0.1:8005, on our dynamically allocated port
reactor.listenUDP(0, MulticastClientUDP()).write('UniqueID', ('224.0.0.1', 8005))
reactor.run()

I've seen alot of discussion about how to correctly do this, so here is an example to give some insight into the basics.

Tags: network