What is SOA?

Service Oriented Architecture (SOA) is causing companies to think seriously about how to assemble their business systems out of common parts. This takes a bit more thought and investment in the beginning, but it enables the companies that use it to build systems faster and faster as the inventory of reusable parts grows.

In a Service Oriented Architecture, systems are composed of reusable components, called "services." A service is a software building block that performs a distinct function — such as retrieving customer information from a database — through a well-defined interface (an electronic description of how to call the service from other services).

SOA is an evolution of client/server architecture. In client/server systems, the functions of user interface, application logic, and data management are separated so that each can be implemented using the platforms and technologies best suited to the task. With SOA, these functions — most typically, the application logic — are decomposed still further. For example, instead of implementing business logic in a monolithic application server, an SOA-based system can transparently incorporate services running on different software platforms, even services hosted externally by a third-party service provider.