Links - The SOA Glossaries at OMG
The OMG ( Object Management Group ) is a consortium that sets standards for object-oriented systems and and model-based architectures.
Perhaps the most interesting page from a standards standpoint is the SOA Glossary.
The SOA glossary, provided by the SOA Community of Practice, contains general definitions of SOA terms as well as links to common definitions in industry and standards organizations such as OMG, Oasis, Open Group and W3C.
The approaches outlined by the four standards organizations have significant variations in tone and content.
The OMG Glossary approaches SOA as "an architectural style for a community of providers and consumers of services". SOA "specifies the contracts to which organizations, people and technologies must adhere in order to participate in the community". The idea of a community is at their core of their conception of SOA.
The Oasis Glossary has a more operative definition - "Service Oriented Architecture (SOA) is a paradigm for organizing and utilizing distributed capabilities that may be under the control of different ownership domains." The needs of people/organizations are met by the capabilities of other people/organizations. The definitions presented in the OASIS Reference Architecture are discussed in more depth in another article on the subject.
The Open Group Glossary seems to target business applications. Among other things, they state that an SAO service is " a logical representation of a repeatable business activity that has a specified outcome (e.g., check customer credit; provide weather data, consolidate drilling reports) ... ". Key concepts are business descriptions and service representations - "including business process, goal, rule, policy, service interface and service component and service orchestration to implement [ a ] service". In any case, SOA-enabled applications "use open standards, realize interoperability and location transparency".
The W3C Glossary takes a more definitive stance by stating that SOA is characterized by five properties:
- Logical view - an abstracted, logical view of actual programs, databases, business processes, etc.
- Message orientation: "formally defined in terms of the messages exchanged between provider agents and requester agents" so that "one does not and should not need to know how an agent implementing a service is constructed".
- Description orientation: "A service is described by machine-processable meta data", documenting the 'semantics' of a service.
- Granularity: "Services tend to use a small number of operations with relatively large and complex messages".
- Platform neutral: "Messages are sent in a platform-neutral, standardized format ...".
All in all, the OASIS organization seems to have the most developed set of SOA definitions, although for some reason the particular definitions cited by the OMG Glossary does not seem to really capture the depth of the Oasis Reference Architecture.