Navigating the SOA Open Standards Landscape Around Architecture – SOA Core Concepts
While the definitions and expressions may differ slightly, the open standards organizations referenced in this document agree on the following fundamental concepts of SOA:
- SOA – SOAs support thinking and organizing in terms of services with distributed capabilities which may be under the control of different ownership domains, and is an architectural style as well as a paradigm for business and IT architecture.
- Service – Services correspond to repeatable activities that can be characterized as capabilities or the access to capabilities, that capabilities satisfy specific needs, that services are self-contained, that services are described, and that access and interaction with services are constrained by policies and contracts. We agree that the service implementation is opaque to service consumers who interact with the service.
- Effect (or real-world effect) – Interacting with services has a purpose and therefore has some outcome which potentially provides exchange of value between consumers and providers.
- Visibility – Participants, more specifically providers with capabilities and consumers with needs, are able to interact with each other. We agree that availability of service descriptions and policies support these interactions.
- Service Description – Services are described with sufficient information in order to determine whether they meet the needs of prospective consumers as well as how to access and interact with them, including but not limited to interfaces, information models, policies, and contracts.
- Policies and Contracts – Service policies represent some constraint, condition, or expectation on the use of services represented by a consuming participant or commitment of a providing participant, and that service contracts represent an agreement by two or more parties.
- Execution Context– In order for services to be invoked, there must be an established path between consumers and providers. In other words, to realize described effects, consumers and providers must acknowledge and comply with a consistent set of agreements in order to have a successful service interaction.
- Interaction – There is some activity involved in making use of capabilities offered by services in order to achieve desired effects.