Web Services: definition

A definition (from: Web Services Architecture - W3C Working Draft 8 August 2003, http://www.w3.org/TR/ws-arch/)

A Web service is a software system designed to support interoperable machine-to-machine interaction over a network. It has an interface described in a machine-processable format (specifically WSDL). Other systems interact with the Web service in a manner prescribed by its description using SOAP-messages, typically conveyed using HTTP with an XML serialization in conjunction with other Web-related standards.

A Web service is an abstract notion that must be implemented by a concrete agent:

1. the agent is the concrete entity (a piece of software) that sends and receives messages
2. the service is the abstract set of functionality that is provided