Enterprise JavaBeans 3.1, 6th Edition

Message-Driven Bean Timers

Message-driven bean timers are similar to stateless session bean timers in several ways. Timers are associated only with the type of bean. When a timer expires, a message-driven bean instance is selected from a pool to execute the timeout callback method. In addition, message-driven beans can be used for performing audits or other types of batch jobs. The primary difference between a message-driven bean timer and a stateless session bean timer is the way in which they’re initiated: timers are created in response to an incoming message or, if the container supports it, from a configuration file.

In order to initialize a message-driven bean timer from an incoming message, you simply put the call to the TimerService.createTimer() method in the message-handling method. For a JMS-based message-driven bean, the method call goes in the onMessage() method:

@MessageDriven
public class JmsTimerBean implements MessageListener {
    @Resource TimerService timerService

    public void onMessage(Message message){
        MapMessage mapMessage = (MapMessage)message;
        long expirationDate = mapMessage.getLong("expirationDate");

        timerService.createTimer(expirationDate, null );
 }

    @Timeout

    public void timeout( ){
        // put timeout logic here
    }

The incoming JMS message should contain information about the timer: the beginning (start) date, duration, or even the Serializable info object. Combining JMS with the Timer Service can offer some powerful design options for implementing audits, batch processing, ...