What Is This SOA All About?

In computing, the term Service-Oriented Architecture (SOA) expresses a perspective of software architecture that defines the use of services to support the requirements of software users. In a SOA environment, nodes on a network[1] make resources available to other participants in the network as independent services that the participants access in a standardized way. Most definitions of SOA identify the use of Web services (i.e. using SOAP or REST) in its implementation. However, one can implement SOA using any service-based technology.

Unlike traditional point-to-point architectures, SOAs comprise loosely coupled, highly interoperable application services. These services interoperate based on a formal definition independent of the underlying platform and programming language (e.g., WSDL). The interface definition encapsulates (hides) the vendor and language-specific implementation. A SOA is independent of development technology (such as Java and .NET). The software components become very reusable because the interface is defined in a standards-compliant manner. So, for example, a C# (C Sharp) service could be used by a Java application.

http://en.wikipedia.org/wiki/Service-oriented_architecture