RPyChat

Sources at http://sebulbasvn.googlecode.com/svn/trunk/rpyc/demos/chat/

RPyChat is a proof-of-concept for a chat client and server. RPyChat is meant to show how everything can be thought of as RPC: when the client logs in, it receives a UserToken object, which the client can use to send text to the server (and the other clients through it). This is a straight forward example of RPC. The key point of RPyChat, however, is that the server also uses RPC to send text to the client — when a client logs in, it also passes a callback function. The server will use this callback function to asynchronously notify the client of events.

Here's a simplified version of the server (the actual server code has some more boilerplate, but other than that, it is very similar):

all_client_callbacks = set()
 
class UserToken(object):
    def __init__(self, name):
        self.name = name
    def exposed_say(text):
        for callback in all_client_callbacks:
            callback("[%s] %s" % (self.name, text))
 
class ChatService(rpyc.Service):
    def exposed_login(self, username, callback)
        all_client_callbacks.add(rpyc.async(callback))
        return UserToken(username)

And the client, minus the GUI boilerplate:

class ChatClient(object):
    def __init__(self, host, port, username):
        # GUI code: create a window with a scrolled textbox called 'history',
        # a textline called 'text', and a button called 'send'
 
        # login code:
        self.conn = rpyc.connect(host, port)
        self.token = self.conn.root.login(username, self.show_text)
 
        # register the connection with the reactor, to be invoked when data is received
        gui_reactor.register_io_read(self.conn, self.background_handler)
 
    def on_send(self):
        self.token.send(self.text.getText())
 
    def background_handler(self):
        self.conn.poll_all() # handle incoming background requests
 
    def show_text(self, text):
        self.history.append(text) # append the new text line to the history

Screenshot

Three clients	Server running in a console