asyncore-example-1.py

import asyncore
import socket, time
# reference time (in seconds since 1900-01-01 00:00:00)
TIME1970 = 2208988800L # 1970-01-01 00:00:00
class TimeRequest(asyncore.dispatcher):
    # time requestor (as defined in RFC 868)
    def __init__(self, host, port=37):
        asyncore.dispatcher.__init__(self)
        self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
        self.connect((host, port))
    def writable(self):
        return 0 # don't have anything to write
    def handle_connect(self):
        pass # connection succeeded
    def handle_expt(self):
        self.close() # connection failed, shutdown
    def handle_read(self):
        # get local time
        here = int(time.time()) + TIME1970
        # get and unpack server time
        s = self.recv(4)
        there = ord(s[3]) + (ord(s[2])<<8) + (ord(s[1])<<16) + (ord(s[0])<<24L)
        self.adjust_time(int(here - there))
        self.handle_close() # we don't expect more data
    def handle_close(self):
        self.close()
    def adjust_time(self, delta):
        # override this method!
        print "time difference is", delta
#
# try it out
request = TimeRequest("localhost")
asyncore.loop()