4. Client/server infrastructure

Distributed processing requires the addition of communication functions. Indeed, the widespread adoption of the client/server model raises specific technical issues, as service calls must be made across a network rather than within a single system, and these systems may be heterogeneous. As a result, these new functions have to be implemented between the client and the server to perform data conversion, localization of the called service, exchange security and transmission (figure 14 ). The following paragraphs explain the need for and principle of these functions.