SOA What? What's the Big Deal About SOA?

Miko Matsumura, DevX.com

SOA is a way of designing systems composed of software components with remotely-callable interfaces. SOA is frequently implemented using coarse-grained, asynchronous, and loosely-coupled pieces of functionality referred to as services. SOA programming falls into three categories: (1) Configuration - using metadata to program intermediaries. (2) Composition
- reusing software components; with composition, applications can be formed by aggregation (for example, having a service that consumes two or more other services synchronously) or by orchestration (a stateful service, which traverses other services serially). Orchestrated services are often workflow-oriented, using standards such as WS-BPEL, and often involve fancy visual tools. Aggregation is the type of composition you most often see in a portal context. (3) Customization - building or changing underlying services. The ability to configure runtime policy at the intermediary level, and the ability to build composite applications, including business process applications, provide a powerful new way to describe business computing.

http://www.devx.com/ibm/Article/29318
See also SOA references: http://xml.coverpages.org/soa.html