Propogate CustomException from servlet

[Maneesh Godbole]

I have an application where the Swing UI client communicates to a servlet using serialized object IO.
My problem is I want to propagate custom exceptions to the UI. I have created a super class extending Throwable and all my custom exceptions subclass it.
Whenever I wanted to throw an exception, it tried wrapping it inside the ServletException/IOException.

On the client side I never get the ServletException but only the IOException.
From the IOException the call to getCause returns null.
Surprisingly I can see my custom exception on the server side stack trace.

What am I doing wrong?

PS. As a workaround I started writing my custom exception to the output stream and the code is working now. But I am sure this is not the correct solution.
[ July 15, 2008: Message edited by: Maneesh Godbole ]