python UDP CS demo

UDP Communication

Contents

1. UDP Communication
   1. Sending
   2. Receiving
   3. Using UDP for e.g. File Transfers
   4. Multicasting?

See also SoapOverUdp, TcpCommunication

Sending

Here's simple code to post a note by UDP in Python:

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1 import socket
2
3 UDP_IP = "127.0.0.1"
4 UDP_PORT = 5005
5 MESSAGE = "Hello, World!"
6
7 print "UDP target IP:", UDP_IP
8 print "UDP target port:", UDP_PORT
9 print "message:", MESSAGE
10
11 sock = socket.socket(socket.AF_INET, # Internet
12                      socket.SOCK_DGRAM) # UDP
13 sock.sendto(MESSAGE, (UDP_IP, UDP_PORT))

Receiving

Here's simple code to receive UDP messages in Python:

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1 import socket
2
3 UDP_IP = "127.0.0.1"
4 UDP_PORT = 5005
5
6 sock = socket.socket(socket.AF_INET, # Internet
7                      socket.SOCK_DGRAM) # UDP
8 sock.bind((UDP_IP, UDP_PORT))
9
10 while True:
11     data, addr = sock.recvfrom(1024) # buffer size is 1024 bytes
12     print "received message:", data

Using UDP for e.g. File Transfers

If considering extending this example for e.g. file transfers, keep in mind that UDP is not reliable. So you'll have to handle packets getting lost and packets arriving out of order. In effect, to get something reliable you'll need to implement something similar to TCP on top of UDP, and you might want to consider using TCP instead.

That being said, sometimes you need to use UDP, e.g. for UDP hole punching. In that case, consider TFTP for python or UDT for python