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The current API needs to be modified to be able to pass back faults for error
conditions. To close this bug, we need to:

1) design an intelligent set of faults that covers conceivable error conditions
and provides a human readable message appropriate for display to users
2) add these faults to the WSDL definitions of the ecogrid apis, making sure to
support both SOAP and HTTP bindings where they exist
3) implement the faults for each of the services (metacat, digir, srb)