On an interview I was given a task to implement a simple messaging system, using timers, message-driven beans and a build tool of my choice. This, of course, had to be implemented at home. All would be deployed on JBoss 5.0. The requirement was short – a timer (EJB) should send random events (exception, warning, info) to a JMS Topic, which should be consumed and handled by an MDB. Each event would be handled in a number of ways, depending on configurations.
You can download the source code (including maven scripts). (To be noted: I didn’t have any prior experience to JMS and MDBs.)