Java™ Network Programming and Distributed Computing

5.7. Building a UDP Client/Server

The previous example illustrates the technical details of how an individual packet may be sent and received. But applications need a series of packets, not just one. The next example shows how to build a UDP server, a long-running system that is capable of serving many requests during its lifetime. The type of service that is provided is an echo service, which echoes back the contents of a packet. The echo service runs on a well-known port, port 7, and if it is known that a system has an echo server installed, the server may be accessed by clients to see if a system is up and running (similar to the ping application). The example below demonstrates how to write an echo client that will send packets to the server ...