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Mon, 15 Mar 2010
A simple asyncore "echo server" example
Tonight I wanted a simple asyncore echo server example for my lecture notes and couldn't immediately find one. Doug Helman has a more complex one in his asyncore Module Of The Week post, but I wanted Just The Basics. So I read up a little and wrote one :-)
First the server:
import asyncore, socket
class Server(asyncore.dispatcher):
def __init__(self, host, port):
asyncore.dispatcher.__init__(self)
self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
self.bind(('', port))
self.listen(1)
def handle_accept(self):
# when we get a client connection start a dispatcher for that
# client
socket, address = self.accept()
print 'Connection by', address
EchoHandler(socket)
class EchoHandler(asyncore.dispatcher_with_send):
# dispatcher_with_send extends the basic dispatcher to have an output
# buffer that it writes whenever there's content
def handle_read(self):
self.out_buffer = self.recv(1024)
if not self.out_buffer:
self.close()
s = Server('', 5007)
asyncore.loop()
And the client:
import asyncore, socket
class Client(asyncore.dispatcher_with_send):
def __init__(self, host, port, message):
asyncore.dispatcher.__init__(self)
self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
self.connect((host, port))
self.out_buffer = message
def handle_close(self):
self.close()
def handle_read(self):
print 'Received', self.recv(1024)
self.close()
c = Client('', 5007, 'Hello, world')
asyncore.loop()
When run the server should display:
Connected by ('127.0.0.1', 56757)
(or similar - the port number will vary) and the client should display:
Received 'Hello, world'
It was actually pretty easy to write, and kinda fun.
