Unfortunatly if it is another application performing the updates then you are fairly constrained about what you can do.
Message Driven Beans need an event to respond to, a change in the db is not going to raise an event to help here. You could possibly set a trigger on the tables that executed a batch file with
java code raising the event via a socket - but that wouldnt be highly elegant either!
It also really depends on the reasons for the application and what the user requirements are. Is there a need for real time data, or is it mainly for periodic reporting anyway?