SOAP - Simple Object Access Protocol, is an XML-based communication protocol and encoding format for inter-application communication.

A SOAP API is defined as a standardized communication protocol for XML-based message exchange. SOAP can use different protocols like HTTP or JMS.

All parameters the server needs to be able to respond to should be a in a W3C standardized XML format and part of the body in the request.

The current specification is version, SOAP 1.2, though version 1.1 is more widespread. SOAP is widely viewed as the backbone to a new generation of cross-platform cross-language distributed computing applications, termed Web Services.