SOAP Building Blocks

A SOAP message is an ordinary XML document containing the following elements:

* A required Envelope element that identifies the XML document as a SOAP message
* An optional Header element that contains header information
* A required Body element that contains call and response information
* An optional Fault element that provides information about errors that occurred while processing the message

All the elements above are declared in the default namespace for the SOAP envelope.


Syntax Rules for SOAP

Here are some important syntax rules:

* A SOAP message MUST be encoded using XML
* A SOAP message MUST use the SOAP Envelope namespace
* A SOAP message MUST use the SOAP Encoding namespace
* A SOAP message must NOT contain a DTD reference
* A SOAP message must NOT contain XML Processing Instructions