Service-oriented architecture (SOA)

Service-oriented architecture (SOA) is the underlying structure supporting communications between services.
SOA defines how two computing entities, usually programs, interact to enable one entity to perform a unit of work on behalf of another entity.

SOA helps create greater alignment between IT and line of business
SOA supports greater business flexibility by generating more flexibility between business and IT
SOA uses task analysis to analyze and improve employee performance through workflows, task and time management, escalations and alerts.

A service-oriented architecture is a collection of services.
These services communicate with each other either by simple data passing or by two or more services coordinating some activity.

Services
Services are what you connect together using Web Services.
A service is the endpoint of a connection and has some type of underlying computer system that supports the connection offered.

The 5 specifications for Web Services are:
Web Services Description Language (WSDL), a format for describing a Web Services interface.
Web Services Dynamic Discovery (WS-Discovery) defines a multicast discovery protocol to locate services.
Web Service Endpoint Language (WSEL) is an XML format for the description of non-operational characteristics of service endpoints.
Web Services Metadata Exchange (WS-MetadataExchange) defines three request-response message pairs to retrieve three types of metadata.
Web Services Policy Framework (WS-Policy) provides a general purpose model and corresponding syntax to describe and communicate the policies of a Web Service

Connections
Web services is the most likely connection technology of service-oriented architectures.
Web services use XML to create a robust connection.