The SOAP envelope contains two parts:
- An optional header providing information on authentication, encoding of data, or how a recipient of a SOAP message should process the message.
- The body that contains the message. These messages can be defined using the WSDL specification.
SOAP commonly uses HTTP, but other protocols such as Simple Mail Transfer Protocol (SMTP) may by used. SOAP can be used to exchange complete documents or to call a remote procedure.
NOTE: SOAP at one time stood for Simple Object Access Protocol. Starting with SOAP Version 1.2, the letters in the acronym have no particular meaning.
Also see how SOAP is used in the ebXML Message Service Specification (MSS).
More information: SOAP page on the W3C website
SOAP and Web Services
The following figure illustrates using SOAP for Web Services. Also see Web Services Explained.
More on the general topic: Messaging Specifications
- Asynchronous Application Service Protocol (ASAP) for SOAP
- Message Service Specification (MSS)
- Representational State Transfer (REST)
- RosettaNet Business Message
- Web Distributed Data Exchange (WDDX)
- Web Services Addressing (WS-Addressing)
- Web Services Eventing (WS-Eventing)
- Web Services Notification (WSN)
- Web Services Reliability (WS-Reliability)
- Web Services Reliable Messaging (WS-ReliableMessaging)
- XML Protocol (XMLP)