4.2.4 Programming in UDP

To send UDP messages, the programmer needs to:

1. Set up a data structure which contains the port number (the process identifier) and the IP address of the destination of the packet.
2. Optionally set up their own source address information - depends on the application.
3. Pass a pointer to the data and the address data structure to the operating system, asking it to construct and send the necessary packet(s).