Service Oriented Architecture (SOA) is a paradigm for organizing and using distributed capabilities that may be under the control of different ownership domains.

Visibility, interaction, and effect are key concepts for describing the SOA paradigm.

For a service provider and consumer to interact with each other they have to be able to 'see' each other. Visibility needs to be emphasized because it is not necessarily obvious how service participants can see each other to interact.

The service interface is the means for interacting with a service. It includes the specific protocols, commands, and information exchange by which actions are initiated that result in the real world effects as specified through the service functionality portion of the service description.

SOA is commonly implemented using Web services, but services can be made visible, support interaction, and generate effects through other implementations.

Service: The means by which the needs of a consumer are brought together with the capabilities of a provider.

Service Description: The information needed in order to use, or consider using, a service.

Service Provider: Makes the service available and publishes the contract that describes the interface to the service and registers the service with a service broker

Service Consumer: Queries the service broker and finds the desired service.

Service Broker: Gives the service consumer directions on where to find the service and its service contract.