Question

I’m a complete Twisted AND Python noob, so my apologies if any of my terminology is wrong or anything I’ve done is silly. Nonetheless….

I’ve implemented my servers in the following way:

def makeServer(application, port):
    factory = protocol.ServerFactory()
    factory.protocol = MyChat
    factory.clients = []
    tempServer = internet.TCPServer(port, factory)
    tempServer.setServiceParent(application)
    return tempServer

application = service.Application("chatserver")
server1 = makeServer(application, port=1025)
server2 = makeServer(application, port=1026)
server3 = makeServer(application, port=1027)

Note that MyChat is an event handling class that has a “receiveMessage” action:

def lineReceived(self, line):
    print "received", repr(line)
    for c in self.factory.clients:
       c.transport.write(message + '\n')

I want server1 to be able to pass messages to server2. Rather, I want server1 to be treated as a client of server2. If server1 receives the message “hi” then I want it to send that same exact message to server2. The only thing server1 needs to be able to do is to send the message it received from its client to server2.

How can I accomplish this?

NOTE: You can totally change the way I’m implementing my server if it helps.

Answer 1

Different parts of your application can interact with each other using method calls.

Send a message to server2 really just means Call a method on one of the objects related to server2.

For example, in MyChat, you might have:

def lineReceived(self, line):
   print "received", repr(line)
   for c in self.factory.clients:
       c.transport.write(message + '\n')
   for server in self.factory.otherServers:
       server.otherServerMessage(self, line)

This supposes a couple things:

• You add a new otherServers attribute to your factory. Its contents are objects related to the other listening servers you have set up. These might be factory objects or protocol objects. It depends on what’s most convenient based on what you intend to do with the message.
• You give those related objects a new method, otherServerMessage, to handle messages delivered this way. If you were to deliver the messages directly to MyChat.lineReceived (which you easily could, if you wanted) then I would expect you to end up with infinite recursion; having a different method lets you differentiate between messages received from a client and messages received from another server.