SOAP Main Features

SOAP Main Features 

1. It is a lightweight protocol for exchange of information in a decentralized, distributed environment.
2. It is the successor of XML-RPC; however it borrows its transport and interaction neutrality and the envelope/header/body from somewhere else.
3. It can form the foundation layer of a web services protocol stack, providing a basic messaging framework upon which web services can be built.
4. It makes use of an Internet application layer protocol as a transport protocol.
5. It can potentially be used in conjunction with a variety of other protocols.

SOAP Message

It is an ordinary XML document which is generally sent to a web service enabled web site along with the parameters required for a search. The site would then send back an XML-formatted document with the resulting data. Since the data is returned in a standardized machine-parseable format, it can then be integrated directly into a third-party site. It basically consists of following four elements:

1. An Envelope element: It is the root element of a SOAP message which identifies the XML document as a SOAP message
2. A Header element: It contains application-specific information such as authentication, payment, etc about the SOAP message. The Header element is optional and if it is present, it must be the first child element of the Envelope element.
3. A Body element: It is the required message element which indicates call and response information. It contains the actual SOAP message intended for the eventual endpoint of the message. Immediate child elements of the SOAP Body element may be namespace-qualified.
4. A Fault element: It is an optional element which consists of errors and status information. It can only appear once in a SOAP message. If a Fault element is present, it must appear as a child element of the Body element.