Service-Oriented Architecture (SOA) describes a set of principles used for designing and developing software in the form of reusable and interoperable components or services.   These SOA services are functions that are well-defined, self-contained, and do not depend on the context or state of other services, i.e., they are loosely coupled.  An application (or service) that is the service consumer will send a request message to another service (the service provider).  The service provider may, in turn, call other services which are also acting as service providers.  Then the service provider will return a response message.

Services may be created and implemented using different programming languages and still be reused by many different applications. The advantage of this architecture is that different areas of an organization or even different companies across an industry can develop and deploy services using their preference of implementation language, and other consuming systems can still use them.  For example, one service may be written in C# while another may be written in Java.

Each SOA service exposes a clearly defined interface that is used to access it and pass information.  These services and their consuming applications communicate with each other through a well-defined, share format, such as XML, to call and pass information between SOA services.  Other data describing notations such as JSON can also be used.