Show the full stack trace
Thanks for the reply - I've just received an answer from somewhere else. Essentially the things that weren't serializable were the Tomcat HttpServletRequest and Response objects in the method signature - passing some other data structure is working fine. Simple when you know how :-/
ps: the full stack trace was quite long - essentially it ran through the tomcat methods and then 'crossed over' into the EJB methods (from the EJB stub, presumably). Not really very helpful, other than telling me it was failing at the call to the EJB.