Folks, I have been digging into the problem of alternative renderings for OGSA-DMI. As per charter we are supposed to deliver at least two different renderings: a) WS-I BaseProfile compliant rendering b) WSRF compliant rendering. Leaving the additional WSRF operations out of the equation for the moment there is indeed a terminal incompatibility between those two renderings. I am not sure about the WS-I part on this picture, but the WSRF part of that picture is as follows, particularly the WSRF BaseFault specification (WS-BaseFaults v1.2). Chapter 3 in the BaseFaults specification defines how BaseFaults (and derived distinguieshed types) MUST be used in WSDL 1.1. Lines 237 to 239 of that specification explicitly links a BaseFault or any of its derived types through a (WS-I compliant!) wsdl:message to a wsdl:operation declaration. In other words, this is a closed link that leaves no room for alternatives. Hence alternative renderings MAY be interoperable on the input and output messages of any genuinely defined operation (such as the DTF's "requestDataTransfer()") but when it comes to faults alternative renderings CANNOT be interoperable as there MUST be a distinctively defined fault element present. I believe that WS-I has similar if not the same requirements. Any expert around here? Having said that I believe that alternative implementations of different renderings will not be interoperable, unless we define interoperability to exclude any fault messages. We might, if we define common wsa:Action values and explicitly allow a CONSUMER (from WS-I Basic Profile 1.1) to ignore the soap:Fault child element. Comments? Cheers, Michel