Abstract: Web programming is very essential to many web applications of digital library,Socket is the base of web programming which creates a virtual pipeline between client and server for data communication.It is also the interface of the application layer and the transmission layer.The principles of socket web programming is introduced in this paper.The author thinks that there will be more and more socket application programs based on TCP/UDP in digital library in the future.

Key words: Digital Library,Socket,Socket Web Programming,TCP/UDP