UDP client and server with Twisted Python

Question

I want to create a server and client that sends and receives UDP packets from the network using Twisted. I\'ve already written this with sockets in Python, but want to take adva

Answer 1

Just like the server example above, there is a client example to. This should help you get started:

• https://twistedmatrix.com/documents/current/core/howto/udp.html
• https://github.com/twisted/twisted/blob/trunk/docs/core/examples/echoclient_udp.py

Ok, here is a simple heart beat sender and receiver using datagram protocol.

from twisted.internet.protocol import DatagramProtocol
from twisted.internet import reactor
from twisted.internet.task import LoopingCall
import sys, time

class HeartbeatSender(DatagramProtocol):
    def __init__(self, name, host, port):
        self.name = name
        self.loopObj = None
        self.host = host
        self.port = port

    def startProtocol(self):
        # Called when transport is connected
        # I am ready to send heart beats
        self.loopObj = LoopingCall(self.sendHeartBeat)
        self.loopObj.start(2, now=False)

    def stopProtocol(self):
        "Called after all transport is teared down"
        pass

    def datagramReceived(self, data, (host, port)):
        print "received %r from %s:%d" % (data, host, port)


    def sendHeartBeat(self):
        self.transport.write(self.name, (self.host, self.port))



class HeartbeatReciever(DatagramProtocol):
    def __init__(self):
        pass

    def startProtocol(self):
        "Called when transport is connected"
        pass

    def stopProtocol(self):
        "Called after all transport is teared down"


    def datagramReceived(self, data, (host, port)):
        now = time.localtime(time.time())  
        timeStr = str(time.strftime("%y/%m/%d %H:%M:%S",now)) 
        print "received %r from %s:%d at %s" % (data, host, port, timeStr)



heartBeatSenderObj = HeartbeatSender("sender", "127.0.0.1", 8005)

reactor.listenMulticast(8005, HeartbeatReciever(), listenMultiple=True)
reactor.listenMulticast(8005, heartBeatSenderObj, listenMultiple=True)
reactor.run()

The broadcast example simply modifies the above approach:

from twisted.internet.protocol import DatagramProtocol
from twisted.internet import reactor
from twisted.internet.task import LoopingCall
import sys, time

class HeartbeatSender(DatagramProtocol):
    def __init__(self, name, host, port):
        self.name = name
        self.loopObj = None
        self.host = host
        self.port = port

    def startProtocol(self):
        # Called when transport is connected
        # I am ready to send heart beats
        self.transport.joinGroup('224.0.0.1')
        self.loopObj = LoopingCall(self.sendHeartBeat)
        self.loopObj.start(2, now=False)

    def stopProtocol(self):
        "Called after all transport is teared down"
        pass

    def datagramReceived(self, data, (host, port)):
        print "received %r from %s:%d" % (data, host, port)


    def sendHeartBeat(self):
        self.transport.write(self.name, (self.host, self.port))



class HeartbeatReciever(DatagramProtocol):
    def __init__(self, name):
        self.name = name

    def startProtocol(self):
        "Called when transport is connected"
        self.transport.joinGroup('224.0.0.1')
        pass

    def stopProtocol(self):
        "Called after all transport is teared down"


    def datagramReceived(self, data, (host, port)):
        now = time.localtime(time.time())  
        timeStr = str(time.strftime("%y/%m/%d %H:%M:%S",now)) 
        print "%s received %r from %s:%d at %s" % (self.name, data, host, port, timeStr)



heartBeatSenderObj = HeartbeatSender("sender", "224.0.0.1", 8005)

reactor.listenMulticast(8005, HeartbeatReciever("listner1"), listenMultiple=True)
reactor.listenMulticast(8005, HeartbeatReciever("listner2"), listenMultiple=True)
reactor.listenMulticast(8005, heartBeatSenderObj, listenMultiple=True)
reactor.run()

Answer 2

Check out the echoclient_udp.py example.

Since UDP is pretty much symmetrical between client and server, you just want to run reactor.listenUDP there too, connect to the server (which really just sets the default destination for sent packets), then transport.write to send your packets.