you can use the annotation @wsdlLocation to bind your SEI (service end point) to a WSDL. That way the SEI has to confirm to the WSDL.
also, you could always do wsgen (WSDL to java) to generate the SEI and the relevant datatypes.
To answer your question about moving your JBossWS 1.0.3 to JBossWS 1.2.x and JBossWS 2.x, I would imagine it would be a relatively painless transition.
You use your webservice interface (from JAX RPC) as your service interface and tag it with the annotation @Webservice. The JBoss runtime should automatically pick it up.
thank you very much for your response!