En Fri, 15 Feb 2008 20:24:19 -0200, 7stud <[EMAIL PROTECTED]> escribió:
> My question pertains to this example: > > #!/usr/bin/env python > > import socket, sys, time > > host = sys.argv[1] > textport = sys.argv[2] > > s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) > try: > port = int(textport) > except ValueError: > # That didn't work. Look it up instread. > port = socket.getservbyname(textport, 'udp') > > s.connect((host, port)) > print "Enter data to transmit: " > data = sys.stdin.readline().strip() > s.sendall(data) > s.shutdown(1) > print "Looking for replies; press Ctrl-C or Ctrl-Break to stop." > while 1: > buf = s.recv(2048) > if not len(buf): > break > print "Received: %s" % buf > > > As far as I can tell, the if statement: > > if not len(buf): > break > > does nothing. Either recv() is going to read some data or it's going > to block. My understanding is that udp sockets do not have a > connection, so the server can't close the connection--hich would cause > a blank string to be sent to the client. > > So, as far as I can tell, the only way that code would make sense is > if the server were programmed to send a blank string to the client > after it sent data to the client. Is that correct? That example is plain wrong; looks like some TCP code but with SOCK_STREAM blindy replaced with SOCK_DGRAM. connect, sendall and recv are not used for UDP; sendto and recvfrom are used instead. There are some examples in the Demo python directory. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
