How does JMS or MDB fit in web services?

J2EE1.4 supports JAX-RPC, which uses HTTP as the transport layer, and its clients can use stubs or DII to access the web services. UDDI and WSDL can be used to register and describe the services.

If I already have a message service using JMS or MDB, how do I turn it to an asynchronous web service?
Can HTTP still be used here? If not, any issues with firewalls? How do WSDL & UDDI play here? Does J2EE1.4 support this type of web services?