SOAP Fault Element

When an error occurs during processing, the response to a SOAP message is a SOAP fault element in the body of the message, and the fault is returned to the sender of the SOAP message.
The SOAP fault mechanism returns specific information about the error, including a predefined code, a description, the address of the SOAP processor that generated

• A SOAP Message can carry only one fault block
• Fault element is an optional part of SOAP Message
• For the HTTP binding, a successful response is linked to the 200 to 299 range of status codes;
• SOAP fault is linked to the 500 to 599 range of status codes.

The SOAP Fault element has the following sub elements:

Sub Element	Description
<faultcode>	A code for identifying the fault
<faultstring>	A human readable explanation of the fault
<faultactor>	Information about who caused the fault to happen
<detail>	Holds application specific error information related to the Body element

SOAP Fault Codes
The faultcode values defined below must be used in the faultcode element when describing faults:

Error	Description
VersionMismatch	Found an invalid namespace for the SOAP Envelope element
MustUnderstand	An immediate child element of the Header element, with the mustUnderstand attribute set to “1”, was not understood
Client	The message was incorrectly formed or contained incorrect information
Server	There was a problem with the server so the message could not proceed

SOAP Fault Example

The following code is a sample Fault. The client has requested a method named ValidateCreditCard , but the service does not support such a method. This represents a client request error, and the server returns the following SOAP response:

<?xml version='1.0' encoding='UTF-8'?>

<SOAP-ENV:Envelope
  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
  xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"
  xmlns:xsd="http://www.w3.org/1999/XMLSchema">
   <SOAP-ENV:Body>
     <SOAP-ENV:Fault>
     <faultcode xsi:type="xsd:string">SOAP-ENV:Client</faultcode>
     <faultstring xsi:type="xsd:string">
          Failed to locate method (ValidateCreditCard) in class
          (examplesCreditCard) at /usr/local/ActivePerl-5.6/lib/
            site_perl/5.6.0/SOAP/Lite.pm line 1555.
        </faultstring>

      </SOAP-ENV:Fault>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

References
1. Wikipedia for SOAP