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Network and Networking Programming free ebook is uploaded at http://www.free-itebooks.com
Below is the excerpt of free programming ebook about network and network programming

The Windows Sockets Application Programming Interface (WinSock API)

The Windows Sockets Application Programming Interface (WinSock API) is a library
of functions that implements the socket interface as popularized by the Berkeley Software
Distribution of UNIX. WinSock augments the Berkeley socket implementation
by adding Windows-specific extensions to support the message-driven nature of the
Windows operating system.


WinSock version 1.1 is bound to the TCP/IP protocol suite. Although future versions
of WinSock are expected to support Novell’s IPX/SPX, Apple’s Appletalk, and other
popular network protocols, this book concentrates on the socket interface to the TCP/
IP protocol stack.


The WinSock specification allows TCP/IP stack vendors to provide a consistent interface
to their stacks so that application developers can write an application to the WinSock
specification and have that application run on any vendor’s WinSock-compatible TCP/
IP protocol stack. This is contrast to the days before the WinSock standard when software
developers had to link their applications with libraries specific to each TCP/IP
vendor’s implementation. This limited the number of stacks that most applications ran
on because of the difficulty in maintaining an application that used several different
implementations of Berkeley sockets. WinSock has removed that barrier. Application
programmers write to the WinSock API and link their applications with the
WINSOCK.LIB import library (or WSOCK32.LIB in the case of Win32). The application
can then be installed on a computer that has a WinSock TCP/IP stack, from any
number of vendors, and dynamically link to the WINSOCK.DLL (or WSOCK32.DLL)
provided by the vendor. Figure 3.1 is a block diagram of WSOCK32.DLL interaction
in a 32-bit program on Windows NT. Although the actual WINSOCK.DLL is specific
to each TCP/IP stack vendor, the interface into that dynamic link library remains consistent,
hence any program linked with the WinSock import library should work.