Provide a standard object invocation protocol built on Internet standards, using HTTP as the transport and XML for data encoding. Create an extensible protocol and payload format that can evolve. A major design goal for SOAP is simplicity and extensibility. SOAP provides a way to access services, objects, and servers in a completely platform-independent manner. SOAP is a wire protocol that can be used to facilitate highly ultra-distributed architecture.
SOAP is simple.
Official W3C SOAP specification is here . In order to utilize a service on a remote server using SOAP, the client needs to understand what the remote service is capable of. Using SDL, SOAP provides a way to query the remote service and learn about its capabilities, such as how it represents data types and commands. For example, using SDL one could learn that a particular service accepts two strings, searches for first string inside second, and returns true or false. Much like SDL, the SOAP Contract Language is designed to expose the capabilities of a service, but also goes much farther.