SOAP (Simple Object Access Protocol)   A World Wide Web Consortium (W3C) standard, lightweight protocol for exchange of information in a decentralized, distributed environment. SOAP is an Extensible Markup Language (XML)-based protocol that consists of three parts: an envelope that defines a framework for describing what is in a message and how to process it; a set of encoding rules for expressing instances of application-defined data types; and a convention for representing remote procedure calls and responses.