notification pattern

I am trying to design an appllication that using dynamic notification to clients upon data store updates (i.e. background threads a,b & c update an event database, and then another ejb notifies gui Z that updates have occurred and either provides the updates or indicates that updates have occurred. Gui Z (could be stand alone java app or applet) then calls an ejb to retrieve the updates for display). The general purpose is to eliminate continually polling the database for new updates.

Is there a design pattern for client registration, update notification, etc for this. I had envisioned using message ejbs for this.

Check the Observer pattern.

Thanks for the reply. Is there an example implementation using jms somewhere?

Is there an example implementation using jms somewhere?

There are plenty of there. Use google.

JMS has a publish-subscribe model that is made for just this. The Sun JMS Tutorial should be a good starting point. Gregor Hohpe has a great collection of messaging patterns.

Looking on the net I haven't found a design pattern that pulls both JMS publish/suscribe and notification/registration. I've seen the later for ejbs, but not incorporating JMS. Short of buying the eai patterns book, is there another resource out there?