Thanks for answering.
I will take a look at the DatabaseObserver Interface. Isn't RMI over TCP/IP sufficient for the task you mentioned?
It boils down to your particular needs. You will have to push notifications via some kind of network transport, so be it RMI or JMS it shouldn't change that much (though JMS is the buzzword of the moment so your product might leverage more marketing fuss ;-)).
Ciao,
-- Gianugo Rabellino
