Client/Server Computing

Client/server computing is a broadly defined term that describes a system architectural configuration. In particular, client/server computing conceptually and physically divides an application into component processes. The ensuing processes work together to satisfy the requirements of the overall application. The particular configuration of the processes describes the client/server system. Three defining classification scenarios are presented. The first classification is based on the presentation–application–data (P–A–D) architecture. P–A–D defines and classifies an application based upon how the computational requirements are distributed between the client and the server. The second classification is based on the number of separate processes (or tiers) that exist within a client/server application. The final classification is based on the functional role of the server process. Client/server processes must interoperate seamlessly. The integration of software and hardware is challenging, particularly in heterogeneous environments. Middleware is an enabling technology that facilitates the intercommunication among software processes. Component software is an approach whereby self-contained, self-describing objects are combined to form applications. Networking technologies bridge the gap among the various computing and networking devices. This chapter concludes with a review of the following client/server implementations: the Internet, intranets, and extranets. Keywords: client/server computing; client/server tier; component model; extranets; Internet protocol stack; intranets; middleware