[Tutor] Learning Python with a Simple IM

[Jorge Louis De Castro]

Hello,

I am a Java Developer that wants to learn Python by doing. I am loving this initial vibe I'm getting out of Python. However, because I feel programmers of a certain languages bring with them certain vices when moving to other languages, I'd like to have feedback from seasoned Python programmers regarding my code.
Using some socket examples I've googled here and there I wrote the very simple Instant-Messaging-wannabe program below. I was advised to post the code here and get feedback from this community.
In my next iteration with this code I'll be changing the client to include a server thread listening instead of polling the server.

Regards
jorge


THE SIMPLE IM CLIENT

import socket, threading, time, msvcrt

print "Please enter the following information"
_url = raw_input("URL: ")
_port = raw_input("Port: ")
print "Starting IIM client on port: " + _port

socketOut = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
socketOut.connect((_url, int(_port)))

# clear screen here

print "Enter your user details"
_from = raw_input("User id: ")
_to = raw_input("Buddy id: ")

print '\n'
print "Connecting to server..."
print '\n'

# send user details and receive response
socketOut.sendall('@@@'+_from+'##'+_to)
response = socketOut.recv(8192)

def listener():
    while 1:
        time.sleep(5)
        socketOut.sendall('$$$'+_from)
        response = socketOut.recv(8192)
        if response != " ":
            print "\n" + response


if response == 'AUTH_OK':
    data = ""
    th = threading.Thread(target=listener)
    th.setDaemon(1)
    th.start()
    print "Background polling thread started"
    while 1:

        if msvcrt.kbhit():
            ch = msvcrt.getche()
        else:
            ch = None
        if ch:
            if ch != '\r':
                data += ch
            else:
                print '\n'
                socketOut.sendall('###'+_from+'##'+data)
                response = socketOut.recv(8192)
                if response != " ":
                    print response
                data = ""

else:
    print "Auhentication failed!"
        
socketOut.close()




THE SIMPLE IM SERVER

import SocketServer

_port = 8881
_clients = {}

# a connected client
class Client:
    # queue of messages sent to this client
    queue = []
    def __init__(self, _sock, _src, _dest):
        print "Creating IM client"
        self.socket = _sock
        print "Incoming socket: %s" % self.socket
        self.user = _src
        print "Username: " + self.user
        # buddies should be a list
        self.buddy = _dest
        print "Buddy: " + self.buddy
        print "Created IM client"

# the server handling requests
class Broker(SocketServer.BaseRequestHandler):
    def handle(self):
        print "Connected from", self.client_address
        while True:
            receivedData = self.request.recv(8192)
            if not receivedData:
                break
            
            # if handshake packet, extract client details
            if receivedData.startswith('@@@',0,3):
                print "Received handshake packet"
                # strip handshake code
                receivedData = receivedData.replace('@@@', '', 1).lstrip()
                l = receivedData.split('##',1)
                socket = self.request
                src = l[0]
                dest = l[1]
                c = Client(socket, src, dest)
                # use username as key on hashmap
                _clients[src] = c
                # send success message
                socket.sendall('AUTH_OK')
                print "Client " + src + " authenticated"

            # if polling packet, extract sender details and send messages
            if receivedData.startswith('$$$',0,3):
                # strip polling message
                print "Received polling packet"
                src = receivedData.replace('$$$', '', 1).lstrip()
                # only poll if more than 1 user
                if len(_clients) > 1:                
                    # use username as key on hashmap
                    _clients[src] = c
                    if len(c.queue) < 1:
                        c.socket.sendall(" ")
                    else:
                        msgs = ""
                        for q in c.queue:
                            msgs += q + '\n'
                            # send queued messages
                        c.socket.sendall(msgs)
                        c.queue = []
                        print "Sent all pending messages for " + c.user
                else:
                    socket.sendall(" ")

            # if message packet, extract data and append to target queue
            if receivedData.startswith('###',0,3):
                print "Received message packet"
                receivedData = receivedData.replace('###', '', 1).lstrip()
                l = receivedData.split('##',1)
                src = l[0]
                text = l[1]
                if text.strip != "":
                    print "Message not empty"
                    # extract client
                    clientSrc = _clients[src]
                    # ...and its buddy
                    clientDest = _clients[clientSrc.buddy]
                    msg = src+": "+text
                    print "Appended message to queue of " + clientSrc.buddy
                    clientDest.queue.append(msg)
                    print "Queue of: " + clientDest.user + " = %s" % clientDest.queue
                clientDest.socket.sendall(" ")
            else:
                if len(_clients) < 2:
                    self.request.sendall(receivedData)

        for c in _clients.values():
            if self.request == c.socket:
                c.socket.close()
                # remove from hashmap
                del _clients[c.user]
                print "Removed " + c.user + " from hashmap"

        print "Disconnected from", self.client_address
        
srv = SocketServer.ThreadingTCPServer(('',_port),Broker)
print "Started IIM server on port %d" % _port
srv.serve_forever()
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