Service-oriented architecture (SOA)

"A service-oriented architecture (SOA) is a style of software design where services are provided to the other components by application components, through a communication protocol over a network. ... A service is a discrete unit of functionality that can be accessed remotely and acted upon and updated independently" (Wikipedia).

"A service-oriented architecture is essentially a collection of services. These services communicate with each other. The communication can involve either simple data passing or it could involve two or more services coordinating some activity. Some means of connecting services to each other is needed" (Douglas K Barry). "In SOA, services use protocols that describe how they pass and parse messages using description metadata" (Wikipedia). "The technology of Web Services is the most likely connection technology of service-oriented architectures" (Douglas K Barry).

"Service-orientation is a way of thinking in terms of services and service-based development and the outcomes of services. A 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)
• Is self-contained
• May be composed of other services
• Is a 'black box' to consumers of the service" — The Open Group

"SOA has two major functions. The first is to create a broad architectural model that defines the goals of applications and the approaches that will help meet those goals. The second function is to define specific implementation specifications" (TechTarget).