Introduction to Winsock

Chapter 1

Introduction to Winsock

This chapter is dedicated to learning the basic techniques for writing successful Winsock applications. Winsock is a standard application programming interface (API) that allows two or more applications (or processes) to communicate either on the same machine or across a network and is primarily designed to foster data communication over a network. It is important to understand that Winsock is a network programming interface and not a protocol. Winsock provides the programming interface for applications to communicate using popular network protocols such as Transmission Control Protocol/Internet Protocol (TCP/IP) and Internetwork Packet Exchange (IPX). The Winsock interface inherits a great deal from the BSD Sockets implementation on UNIX platforms. In Windows environments, the interface has evolved into a truly protocol-independent interface, especially with the release of Winsock 2.

In this chapter, we'll look at the fundamentals of setting up communication from one machine on a network to another, along with how to send and receive data. The examples presented in this chapter help to provide an understanding of the Winsock calls that are required for accepting connections, establishing connections, and sending and receiving data. Because the purpose of this chapter is to learn these fundamental Winsock calls, the examples presented use straight blocking Winsock calls. Chapter 5 presents non-blocking and other advanced I/O methods available in Winsock, including code examples.

In addition, in this chapter we will present both the Winsock 1 and Winsock 2 versions of the various API functions. You can differentiate the two functions with the WSA prefix. If Winsock 2 updated or added a new API function in its specification, the function name is prefixed with WSA. For example, the Winsock 1 function to create a socket is simply socket. Winsock 2 introduces a newer version named WSASocket that is capable of using some of the new features made available in Winsock 2. There are a few exceptions to this naming rule. WSAStartup, WSACleanup, WSARecvEx, and WSAGetLastError are in the Winsock 1.1 specification.

Before you begin developing an application using Winsock, you need to understand what files and libraries are required to build your application.