Sockets form the underpinnings of almost all networking protocols. JDBC,
RMI, CORBA, EJB, and the non-Java RPC (Remote Procedure Call) and NFS
(Network File System) are all implemented by connecting various types of
sockets together. Socket connections can be implemented in many
languages, not just Java: C, C++, Perl, and Python are also popular, and
many others are possible. A client or server written in any one of these
languages can communicate with its opposite written in any of the other
languages. Therefore, it's worth taking a quick look at how the
ServerSocket behaves, even if you wind up
utilizing the higher-level services such as RMI, JDBC, CORBA, or
The discussion looks first at the
ServerSocket itself, then at writing data over
a socket in various ways. Finally, we show a complete implementation of
a usable network server written in Java: the chat server from the client
in the previous chapter.
You need to write a socket-based server.
for the given port number.
the "other end" of a connection, the server that waits patiently for
clients to come along and connect to it. You construct a
ServerSocket with just the port
number. Since it doesn't need to connect to another host, it
doesn't need a particular host's address as the client socket
ServerSocket constructor doesn't throw ...