The most common form of distributed application is the client-server model. In this scheme, client processes request services from a server process.
An alternate scheme is a service server that can eliminate dormant server processes. An example is inetd(1M), the Internet service daemon. inetd(1M) listens at a variety of ports, determined at startup by reading a configuration file. When a connection is requested on an inetd(1M) serviced port, inetd(1M) spawns the appropriate server to serve the client. Clients are unaware that an intermediary has played any part in the connection. inetd(1M) is described in more detail in inetd Daemon.