Note: Many topics at this site are reduced versions of the text in "The Encyclopedia of Networking and Telecommunications." Search results will not be as extensive as a search of the book's CD-ROM.

APIs are the language and messaging formats that define how programs interact with an operating system, with functions in other programs, with communication systems, or with hardware drivers. For example, an operating system provides a set of standard APIs that programmers can use to access common functions such as accepting user input, writing information to the screen, or managing files. The APIs in Microsoft Windows are quite sophisticated because they allow programmers to build programs that easily access features such as pull-down menus, icons, scroll bars, and more. In the network environment, APIs are available that interface network services for delivering data across communication systems. A cross-platform API provides an interface for building applications or products that work across multiple operating systems or platforms.

Several types of network communication APIs are conversational, RPC (remote procedure call), and message APIs. IBM's APPC (Advanced Program-to-Program Communications) model is conversational. RPC models have been developed by Sun Microsystems, by the OSF (Open Software Foundation), and by Microsoft in its Windows environment. Messaging models include IBM MQSeries and MSMQ (Microsoft Message Queue Server).

For example, MSMQ is a store-and-forward service that enables applications running at different times to communicate across networks and systems that may be temporarily offline. Applications send messages to MSMQ, and MSMQ uses queues of messages to ensure that the messages eventually reach their destination. MSMQ provides guaranteed message delivery, efficient routing, security, and priority-based messaging.

Copyright (c) 2001 Tom Sheldon and Big Sur Multimedia.
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