SOAP Cheat Sheet

SOAP is a popular protocol for accessing a web service. My interest in this arose when I needed to schedule a web service using the Oracle Scheduler. This SOAP client had to be written from scratch using PL/SQL so I needed to become familiar with the protocol first.

This is a summarized form of the SOAP Tutorial.

SOAP is an XML dialect so the XML Cheat Sheet might be useful and in particular the XML Namespaces section .

For reference here are the SOAP Specifications .

  • The Simple Object Access Protocol (SOAP) is a simple XML based protocol to let apps exchange information over HTTP.
  • SOAP is a W3C standard, the latest version is 1.2. SOAP is also a major part of .NET .


  • A SOAP message
    • MUST contain an envelope root element
    • MAY contain a header element
    • MUST contain a body element
    • MAY contain a fault element
    • MUST use the SOAP Envelope and a SOAP Encoding namespaces.
  • This is a sample SOAP message.
<?xml version="1.0"?>
<soap:Header> ... </soap:Header>
  <soap:Fault> ... </soap:Fault>


  • There are three attributes in the SOAP envelope namespace :
    • actor - URI of endpoint for which the element is intended
    • mustUnderstand - 0 or 1 to specify whether the receiver is obligated to recognize the element or not.
    • encodingStyle

Fault Elements

The optional SOAP Fault element is used to hold error and status information for a SOAP message. It can have the following sub-elements :

  • faultcode - A code for identifying the fault. The faultcode must be one of the following :
    • VersionMismatch - Found an invalid namespace
    • MustUnderstand - A required element was not understood
    • Client - There was an error in the message
    • Server - There was an error on the server processing the message
  • faultactor - The endpoint that caused the fault
  • faultstring - A human-readable explanation
  • details - Application-specific error info
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