SOAP Syntax

SOAP Building Blocks

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

• Required Envelope element, which identifies this XML document as a SOAP message
• Optional Header element, which contains header information
• Required Body element, which contains all call and response information
• Optional Fault element, which provides information about errors that occurred while processing this message

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

http://www.w3.org/2001/12/soap-envelope

And the default namespace for SOAP encoding and data types:

http://www.w3.org/2001/12/soap-encoding

Syntax Rules

Here are some important syntax rules:

• SOAP messages must be encoded in XML
• SOAP messages must use the SOAP Envelope namespace
• SOAP messages must use the SOAP Encoding namespace
• SOAP messages must not contain DTD references
• SOAP messages must not contain XML processing instructions

Basic Structure of a SOAP Message