You can specify the faultName and message attributes of the bpelx:postAssert element, as shown in the schema definition in the following example for BPEL 1.1.

<invoke | receive | onMessage>
    standard-elements
    <bpelx:postAssert name="ncname"? expression="boolean-expr" faultName="QName"+
 message="generic-expr"+/> *
</invoke | receive | onMessage>

The following example shows the syntax for the faultname and message attributes.

<bpelx:postAssert name="Assert_2"
   message='multiple post assert Greater value fired'
   faultName="ns2:GreaterValue"
  expression="bpws:getVariableData('invar','payload','/ns1:process/ns1:input') <
 500"/>

If you do not specify the faultName attribute, the fault defaults to bpelx:postAssertFailure. If the message attribute is not specified, the message value defaults to the name of the activity.

<bpelx:postAssert expression="boolean-expr" />

The specified fault is thrown whenever the assertion condition evaluates to false. Analysis is performed on the faultName QName to ensure that it properly resolves to a fault that is defined in the partner WSDL portType. The message expression is a general expression that can evaluate to any XPath value type (string, number, or boolean). If a nonstring value is returned, the string equivalent of the value is used.