(1) A self-contained, self-describing modular application that can be published, discovered, and invoked over a network using standard network protocols. Typically, XML is used to tag the data, SOAP is used to transfer the data, WSDL is used for describing the services available, and UDDI is used for listing what services are available.
(2) An application that performs specific tasks and is accessible through open protocols such as HTTP and SOAP.