Ali Arsanjani is Chief Architect from IBM (SOA and WebServices center). This article posted in Dec’2004 is still up to date and it is a good start point if you are new in SOA. Starting with the conceptual model of a SOA architectural style, showed in the figure below:
And this is the Ali’s vision about the layers in a SOA typical architecture (and believe me it is valid today!):
A good article about the basic SOA principles and components definition.
At Sandy Carter blog I’ve found another good SOA dictionary. See the definitions for the most common SOA terms:
Service – a repeatable business task represented by a software module deployed on network accessible platforms provided by the service provider. Its interface is described by a service description. It exists to be invoked by or to interact with a service requestor. It may also function as a requestor.
Service Orientation – an approach to integrate business tasks as loosely coupled, linked services
Service Oriented Architecture –An architectural style of the structure of a software system in terms of its components and the services they provide, without regard for the underlying implementation of these components, services and connections between components
Composite application – a set of related & integrated services that support a business process built on an SOA
Components – Definition of a modular unit of functionality, accessed through one or more interfaces. A component may be composed of other components, but a component is not necessarily a service.
Service Component Architecture (SCA) – a set of specifications which describe a model for building applications and systems using a Service-Oriented Architecture. SCA extends and complements prior approaches to implementing services, and SCA builds on open standards such as Web services.
Business Process Management – Covers the full range of application-to-application, inter-application, workflow and person-to-person process management, including process design, automation, management, and continuous improvement.
Service Registry – a searchable registry of service descriptions where service providers may publish their service descriptions. Service requestors may find services and obtain binding information (in the service descriptions) for services during development for static binding or during execution for dynamic binding.