“SOAP is a protocol specification for invoking methods on servers, services, components and objects. SOAP codifies the existing practice of using XML and HTTP as a method invocation mechanism. The SOAP specification mandates a small number of HTTP headers that facilitate firewall/proxy filtering. The SOAP specification also mandates an XML vocabulary that is used for representing method parameters, return values, and exceptions.” [DevelopMentor] “SOAP is the Simple Object Access Protocol, a way to create widely distributed, complex computing environments that run over the Internet using existing Internet infrastructure. SOAP is about applications communicating directly with each other over the Internet in a very rich way.” [MS] [In the context of the Microsoft Windows DNA 2000 solution]: “The key enabler for Microsoft’s vision of integrated, programmable Web services is XML. Through the exchange of XML messages, services can easily describe their capabilities and allow any other service, application or device on the Internet to easily invoke those capabilities. To help realize that vision, Microsoft today is submitting to the Internet Engineering Task Force (IETF) an Internet draft specification for the Simple Object Access Protocol (SOAP), an XML-based mechanism that bridges different object models over the Internet and provides an open mechanism for Web services to communicate with one another.” More
