Best practice to create a WS in front of rmi-clients?

Hello guys!

I'm looking for the best way to create a webservice in front of a rmi-client.

You see we got system A, java 1.6 and jboss 5.0, that communicates with system B, java 1.6 and jboss 5.0, over remote ejb (RMI I guess).

For a long time ago developers from system B have provided a system-B-ejb-client.jar for developers in system A to use for the communication.

How ever now we need to upgrade system A to java 1.7 and jboss 5.2 and then the RMI does not work any more. Further more RMI is not accepted anymore in the integration architecure.

System B do not got any resources to upgrade as well or do any changes in system B at all. (It look's like they can not even present the source code!)

Therefore this might look like a solution:
We move the system-B-ejb-client.jar into system B itself. But infront, inside of system B, we put a webservice that forwards the request by calling the ejb with the system-B-ejb-client.jar.

But is there a way to maven-auto-generate a webservice upon class-files from a ejb-client-jar-file, like contract last?

Or do you guys see any easier solution?

Best regards
Fredrik