[Tutor] Talking to UDPServer

[Carroll, Barry]

Kent, Johan:

Thank you.  These examples will be a great help.  I also found some links
via Google (I always forget that resource for some reason).  I have enough
to go forward, now.  

Barry


> -----Original Message-----
> From: Johan Geldenhuys [mailto:johan at accesstel.co.za]
> Sent: Tuesday, November 01, 2005 11:39 AM
> To: Kent Johnson
> Cc: Carroll, Barry; 'tutor at python.org'
> Subject: Re: [Tutor] Talking to UDPServer
> 
> I've done some network programming mostly with TCP and I don't think
> that the way the client connects to the server is a lot different (if
> any), The only difference is when you must decide the protcol family.
> "socket.SOCK_DGRAM" will be for UDP and "socket.SOCK_STREAM" will be for
> TCP. After this, the client can connect the same way.
> 
> Here is a simpler sample than the one Kent gave:
> 
> """
> from socket import *
> 
> HOST = 'localhost'
> PORT = 3001
> BUFSIZ = 1024
> ADDR = (HOST, PORT)
> 
> tcpCliSock = socket(AF_INET, SOCK_STREAM) # change here for UDP
> tcpCliSock.connect(ADDR)
> 
> while 1:
>     data = raw_input('>') # Enter text to be transmitted to the server.
>     if not data: break
>     tcpClisock.send(data)
>     data = tcpCliSock.recv(BUFSIZ)
>     if not data: break
>     print data
> 
> tcpCliSock.close()
> """
> HTH,
> 
> Johan
> 
> 
> Kent Johnson wrote:
> 
> > Carroll, Barry wrote:
> >
> >> Yes, that is exactly what I want.  I need to write a program that
> >> communicates with an existing server, using the UDP protocol.  This
> >> is my first time writing such a program, and I need help getting
> >> started.
> >
> >
> > Here is an example from Python Network Programming, by John Goerzen.
> > It opens a UDP port, sends a message, then echoes any received text to
> > the console. There is no higher-level support built in to Python, you
> > just open a datagram socket and push data out. Google for "Python udp"
> > for more examples.
> >
> > Kent
> >
> > #!/usr/bin/env python
> > # UDP Example - Chapter 2
> >
> > 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
> >
> >