5 - Soap

Abstract

Simple Object Access Protocol (SOAP) is a totally Extensible Markup Language (XML)-centric messaging scheme that can be formally characterized as a lightweight communications protocol for exchanging XML-based information among applications in a decentralized, distributed environment. SOAP is used to send input to and receive output from Web services—given that XML Web services operate via exchanging XML documents. Because a Web service requires input parameters to be activated, SOAP is also considered to be what invokes a Web service—given that it is what delivers the input parameters. While it is theoretically possible to have Web services that do not use SOAP, today's conventional wisdom is that SOAP is a mandatory prerequisite for XML Web services at least for the next 4 to 5 years. The role and scope of SOAP, however, are not limited to Web services. SOAP is the latest in a long line of distributed computing initiatives, which in this context includes CORBA and Microsoft's component object models/distributed component object models (COM/DCOM), though it is not meant to totally displace either of these powerful and object-oriented methodologies.