Client-Server Model

The server basically sleeps, waiting to be contacted by clients. There are 2 kinds of servers:

• �[Iterative:] for short jobs. E.g., serve time of day.
• �[Concurrent:] for long services. It typically uses the UNIX fork�� and perhaps exec�� system calls.

SERVER PROGRAM:

1. �Open communication channel and inform local host that it is waiting at some (well-known) port.
2. �Waits for clients.
3. �Serves clients (perhaps after forking)
4. �Goes back to waiting.

CLIENT PROGRAM:

1. �Open communication channel and connects to a server port.
2. �Sends request to server.
3. �Receives response.
4. �Close channel.