public void registerHandler( short objId, RpcHandler handler ) {
        handlers.put(objId, handler);
    }
Register a handler that can be called by the other end
 of the connection using the specified object ID.  Only one
 handler per object ID can be registered at any given time,
 though the same handler can be registered for multiple object
 IDs.
jme3-networking/src/main/java/com/jme3/network/service/rpc/RpcConnection.java