21.1 Socket Domains
Currently there are two available domains, unix and
internet.
The communication in the unix domain is limited
to a single machine running under an Unix operating system, and the sockets
are associated
to files in this machine's file system.
The internet domain can be used to connect any two machines
which are connected through the network. It can also connect two processes
on the same machine.
The address of a socket is then identified
by the host name and the port number.
The host name is the same as obtained e.g. with the
get_flag(hostname, Host).
The port identifies the channel on the host which is used
for the communication. This is available under both Unix and Windows
operating systems.