gistfile1.py

# Shamelessly stolen from the Twisted site

from twisted.internet import protocol, reactor, defer
from twisted.protocols.basic import LineReceiver
from twisted.internet.endpoints import TCP4ServerEndpoint

import json


class JsonEchoServer(LineReceiver):

    """
    Implements the server-side mechanisms
    """
    def __init__(self, *args):
        # LineReceiver.__init__(self, *args)
        self.acks = {}
        self.msgid = 0

    
    def connectionMade(self):
        print "Connected!"
        msg = {"from": "server", 
               "message": "connected", 
               "id": self.msgid}
        self.sendLine(json.dumps(msg))
        self.acks[self.msgid] = msg
        self.msgid += 1


    def lineReceived(self, line):
        """Receives a line from our remote"""
        print "Line!"
        m = None
        try:
            m = json.loads(line)
        except json.JSONDecodeError as e:
            self.sendLine(json.dumps(
                {
                    "from": "server",
                    "message": "json parse error {error}".format(e),
                    "addr": self.addr
                }
                ))
            print "received non-json-decodable string"
            return

        self.sendLine(json.dumps({"acknowledge": m["id"]}))
        self.sendLine(json.dumps(
                { "from": "EchoServer", "message": "%s said '%s'" % ( m["from"], m["message"] ) }
            )
        )
        self.relay(m)

    def send(self, msg):
        self.sendLine(json.dumps(msg))
        

class EchoFactory(protocol.Factory):
    def __init__(self, *args):
        self.peers = []
    def buildProtocol(self, addr):
        e = JsonEchoServer()
        e.addr = addr
        e.factory = self
        self.peers.append(
                {"addr": addr,
                 "proto": e}
                )
        return e

    def relay(self, msg, origin):

        for peer in peers:
            if peer["addr"] == origin:
                continue
            peer["proto"].send(msg)


endpoint = TCP4ServerEndpoint(reactor, 1235)
endpoint.listen(EchoFactory())
reactor.run()

and the RPC client:
https://gist.github.com/aurynn/10309576