The Semantic Side of Service-Oriented Architectures

Background

By nature, all large systems are heterogeneous, i.e. they lack uniformity. These systems were initially developed with different purposes, and evolved towards accretions of different platforms, programming languages and even middleware. SOA paradigm aims at dealing with heterogeneous systems in a decentralised way as much as possible. Decentralisation helps to obtain loose coupling. SOA key technical concepts are services, loose coupling and interoperability. We briefly describe these three concepts below.

Although several definitions exist, in short, a service is an information technology (IT) representation of self-contained business functionality.

Loose coupling minimises dependencies and thus helps scalability, flexibility and fault tolerance. When dependencies are reduced, modifications have minimised effects and the systems still run when part of them are down. When problems occur, it is important to decrease their effects and consequences. Josuttis (2007) elaborates on several strategies to apply loose coupling.