Due to global networks, heterogeneous information systems, and the need for agility, conventional architectures have evolved. The tasks of building entirely new applications, making specific adaptors for legacy systems, or rewriting existing applications are now obsolete. Largely promoted by Web services connectivity, the service-oriented architecture (SOA) is now considered the preferred approach to designing an information system.
SOA proposes to provide existing functions of an information system as "services" that can be accessed in a loosely coupled way, independently from the technical platform. An application is seen as an orchestration of requests for those services. That is why an SOA generally comes with workflow or orchestration concepts.
