-APUE-:
fig16.9, connect with retry.
fig16.10, initialize a socket endpoint for use by a server.
-APUE-:
fig16.14, client command to get uptime from server.
fig16.15, server program to provide system uptime.
fig16.16, server program illustrating command writting
          directly to socket.
-APUE-:
fig16.17, client command using datagram service.
fig16.18, server providing system uptime over datagrams.