If you make the classes implement the Serializable interface, then the rest should take care of itself. There's an example of this in the Redbook Weather Service, where the user-defined datatype Weather is passed in and passed out, both in
unit form and in array form. The only thing I can see enabling this is the Serializable implementation.
I know that the Redbook examples are for WebSphere, but the download does contain fully blown-out versions of their resulting services, and they're JAX-RPC (JSR 109) compliant, so they should work with the other frameworks as well.
Doug Hoople
MCSD.NET, MCDBA, MCSE, MCT, SCJP1.4