Logical Data Validation in Axis2

[Nathan Hook]

We need to do logical data validation for our published web services and we're not exactly sure where to put this logic.

For example we have a web service that will add new users to our system, but each user must have a unique username. So when adding a new user we must check to see if the new username is available (requiring a database hit). If not, we need to send be an error or a fault.

I was thinking of using an Axis2 Handler for the job, but I don't seem to be able to return an error or a fault inside of the Handlers.

Any friendly help or a push in the right direction is appreciated.