#!/usr/bin/env python # encoding: utf-8 # # Copyright (c) 2010 Doug Hellmann. All rights reserved. # """Server half of echo example. """ #end_pymotw_header import select import socket import sys import Queue # Create a TCP/IP socket server = socket.socket(socket.AF_INET, socket.SOCK_STREAM) server.setblocking(0) # Bind the socket to the port server_address = ('localhost', 10000) print >>sys.stderr, 'starting up on %s port %s' % server_address server.bind(server_address) # Listen for incoming connections server.listen(5) # Sockets from which we expect to read inputs = [ server ] # Sockets to which we expect to write outputs = [ ] # Outgoing message queues (socket:Queue) message_queues = {} while inputs: # Wait for at least one of the sockets to be ready for processing print >>sys.stderr, '\nwaiting for the next event' readable, writable, exceptional = select.select(inputs, outputs, inputs) # Handle inputs for s in readable: if s is server: # A "readable" server socket is ready to accept a connection connection, client_address = s.accept() print >>sys.stderr, 'new connection from', client_address connection.setblocking(0) inputs.append(connection) # Give the connection a queue for data we want to send message_queues[connection] = Queue.Queue() else: data = s.recv(1024) if data: # A readable client socket has data print >>sys.stderr, 'received "%s" from %s' % (data, s.getpeername()) message_queues[s].put(data) # Add output channel for response if s not in outputs: outputs.append(s) else: # Interpret empty result as closed connection print >>sys.stderr, 'closing', client_address, 'after reading no data' # Stop listening for input on the connection if s in outputs: outputs.remove(s) inputs.remove(s) s.close() # Handle outputs for s in writable: try: next_msg = message_queues[s].get_nowait() except Queue.Empty: # No messages waiting so stop checking for writability. print >>sys.stderr, 'output queue for', s.getpeername(), 'is empty' outputs.remove(s) else: print >>sys.stderr, 'sending "%s" to %s' % (next_msg, s.getpeername()) s.send(next_msg) # Handle "exceptional conditions" for s in exceptional: print >>sys.stderr, 'handling exceptional condition for', s.getpeername() # Stop listening for input on the connection inputs.remove(s) if s in outputs: outputs.remove(s) s.close()