OVERVIEW

The last decade of the 20th century was witness to an enormous development of computer and communications systems. As processor speeds, memory sizes, and transmission rates were increasing at a seemingly exponential pace, they have progressively enabled ever more powerful computer-based systems. The Information Age is in full swing, symbolized most dramatically by the advent of the Internet and its explosive proliferation. Technology now pervades business, academia, and indeed our entire society. Computers collect and process vast collections of data. Fast communications networks mediate information exchange among computers and data sharing among users. It is not rare today to process a computer program on multiple processors simultaneously (parallel computing), or on a number of networked computers simultaneously (distributed computing).

Computer networks consist of computer nodes, called hosts. A common computer-network architecture is the client/server configuration, dating back to the 1980s. Here, a client is a host playing the role of a requester of services, while a server is a host providing the requisite service, and the two interact over a communications network. A host can be a client, a server, or both, depending on the system configuration. The client/server architecture is versatile, message based, and modular so as to improve the following aspects (Menasce et al. [1994]):

Usability the ease with which a user can learn to operate, prepare inputs for, and interpret outputs from a system or component

Flexibility the ease with which a system or component can be modified for use in applications...