python-websocket

python-websocket is a Python/asyncore WebSocket client library.

Why would I want to use WebSocket over plain TCP for my desktop app?

While the primary intention of the WebSocket protocol is to enable "TCP-like" full-duplex communication from within a web apps, it also provides a number of benefits (over plain TCP) for desktop apps:

• the WebSocket client library is responsible for message parsing, and exposes a simple, event-driven API.
• WebSocket connections are firewall- and proxy-friendly as they are simply upgraded HTTP connections.
• HTTP cookies can be attached to the WebSocket handshake, where they can be used for e.g. authentication.

Usage

def my_msg_handler(msg):
  print 'Got "%s"!' % msg

socket = WebSocket('ws://example.com/demo', onmessage=my_msg_handler)
socket.onopen = lambda: socket.send('Hello world!')

try:
  asyncore.loop()
except KeyboardInterrupt:
  socket.close()

API reference

WebSocket(url, protocol=None, cookie_jar=None, onopen=None, onmessage=None, onerror=None, onclose=None)

Returns a WebSocket connected to a remote host at the given url. In order to allow communication over this socket, asyncore.loop() must be called by the client.

The optional protocol parameter can be used to specify the sub-protocol to be used. By providing a cookie_jar (cookielib), appropriate cookies will be sent to the server.

The remaining parameters are callback functions that will be invoked in the following manner:

onopen:    invoked when a connection to the remote host has been
           successfully established

onmessage: invoked when a message is received (passing the
           received data as an argument to the callback 
           function)

onerror:   invoked when a communication error occured (passing 
           an Exception instance as an argument to the callback 
           function). If onerror is not provided, the default 
           asyncore behavior is used (raising the exception)

onclose:   invoked when the connection has closed _normally_ (by
           request from either client or server)

WebSocket.send(data)

Sends data through the socket.

WebSocket.close()

Closes the socket.