Design of Exception handling on Web Services

[Jesus Angeles]

This topic is brought by my thoughts on how to design a good exception/error system in a web service client and server system. The issues are below:

1. Should we return a String or a business class, etc. instead of a 'throw'n exception on web service interfaces? Should we leave the exception throwing, for web service layer (nothing to do with business layer), e.g. failure to connect to server?

e.g.
Result performService(Request)
where Result can represent an exception standard, in addition to being the no-error result

instead of

Result performService(Request) throws MyServiceException

2. java.lang.Exception's parent Throwable, has the field non-transient java.lang.StackTraceElement. java.lang.StackTraceElement doesnt have an empty constructor. It is causing a failure when trying to pass a java.lang.Exception from server to client, as a 'thrown' object (i.e. declared in 'throws' clause).

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(These came when I was using Xfire to serve the service, and axis to generate the client. I am not sure if this is the same with other implementations.)

[Jesus Angeles]

My current workaround is:

Extend java.lang.Exception, adding a field 'String causeClass'. causeClass will contain the full class name of the Throwable inside the java.lang.Exception.cause field. (My business exception is in that java.lang.Exception.cause field.)

The client evaluates the string causeClass inside the thrown exception class.