Simon Fell > Its just code > Fault Codes

This one has come up on the axis-users mailing list a few times recently, and as my views seem to differ from other views there, I thought I'd throw mine out here to a wider audience. A SOAP Fault consists of a fault code QName, a faultstring and a detail element which can contain arbitrary namespaced xml. JAX-RPC likes to have you map java exceptions to structures in the detail element, whilst I'm not entirely against that, I am against using it while ignore the standard stuff, its not uncommon to see soap faults like this (envelope stuff ignored for clarity).

<faultCode>soap:Server</faultCode>
<faultString />
<detail>
 <j:someException>
  <j:exeception>invalidDate</j:exception>
  <j:message>i don't like mondays</j:message>
 </j:someException>
</detail>

uggghhh, it works, but to me its pretty hideous, if your toolkit of choice doesn't support the fault elements in WSDL and/or map the faults back to exceptions (say .NET for example), as a client programmer your left with the job of grunging around in the detail element XmlNode to get the error info, now compare it to this one.

<faultCode>j:invalidDate</faultCode>
<faultString>i don't like mondays</faultString>

Contains exactly the same amount of useful information but with the added bonus that every toolkit I've looked at will make it easy to access this info.