fault name="NegativeCredit" ... what does fault tag mean

Question

Hi ,
I was trying to understand the code generated for the CreditRating Service sample available with BPEL 10.1.2.
Can anyone please explain what does the tag <fault> here mean. Does this get taken as an input variable into the 'process' method(operation). This is the first time I am seeing a fault tag along with the portType, I have come across input and output messages before, though not the fault tag. There is no explanation for the <fault> tag in the developer guide. Can anyone please explain.
<portType name="CreditRatingService">
<operation name="process">
<input message="tns:CreditRatingServiceRequestMessage"/>
<output message="tns:CreditRatingServiceResponseMessage"/>
<fault name="NegativeCredit" message="tns:CreditRatingServiceFaultMessage" />
</operation>
</portType>

Answer 1

Hi. This means operation "process" is synchronous, has input (naturally) = wait for message described type, has output = replies to client with described message, has fault = can add fault message to ouput message.
I think that this way client haven't to parse output message to decide whether fault is occurred.
Imagine synchronous process with catch branch. Standard Reply at the end of process has output and hasn't fault but in catch branch you can put another Reply with same output and fault. If process run out without exception, client get output message. If exception is occurred then client get output message with fault.