Programming with sockets

Programming with sockets

The sockets interface was first introduced as part of the Berkeley 4.2 Software Distribution. A significant application base has been written using this interface. Socket support was added to UNIX System V Release 4 as part of the BSD/System V unification. The sockets interface is supported by the shared library libsocket.so in Release 6.0.0, which is based on UNIX System V Release 4.2 MP.

Different approaches are possible within the sockets framework. This section discusses these approaches and then illustrates them with a series of sample programs. The programs demonstrate the use of both datagram socket and stream socket communication. This topic is divided as follows:

``Basics'' introduces the sockets routines and the basic model of communication.
``Supporting routines'' describes some of the library functions that may be used to build distributed applications.
``Client/Server model'' discusses the model used in developing applications and includes examples of the two major types of servers.
``Advanced topics'' discusses issues that may be relevant for more sophisticated users.
``Moving to IPv6'' discusses issues relevant to writing new sockets based applications using the IPv6 addressing scheme and related functions.
``Sockets migration and sockets-to-XTI conversion'' discusses issues relevant to porting a sockets application to XTI.

NOTE: The new issues raised by IPv6 support in Release 6.0.0 are fully covered in ``Moving to IPv6''. No references are made to IPv6 in earlier topics to avoid confusing those new to the sockets environment, who only need to understand the basic principles.