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timeoutejb
omnomnom
omnomnom

Reputation: 9149

EJB Timer Service: order of timeouts

I have two timeouts defined:
timeout A - every 30 seconds
timeout B - every 2 minutes

// scheduled for timeout A (every 30sec)
@Stateless
public class MyBeanA {
   (...)

   @Timeout
   public void onTimeoutA(javax.ejb.Timer timer) {
     // (...)
   }
}

// scheduled for timeout B (every 2min)
@Stateless
public class MyBeanB {
   (...)

   @Timeout
   public void onTimeoutB(javax.ejb.Timer timer) {
     // (...)
   }
}

It's easy to notice, that after every 2 minutes, both timeouts will be fired. I'd like to make sure that in this case, timeout A will be fired before timeout B:
(30sec): timeoutA, (60sec): timeoutA, (90sec): timeoutA, (120sec): timeoutA, timeoutB

Is it possible with standard EJB (3.0) Timer Service API? My application server is JBoss.

Thanks in advance, Piotr

Upvotes: 0

Views: 1474

Answers (2)

omnomnom
omnomnom

Reputation: 9149

Solution I used is very similar to the one given by bkail. There is one ejbTimeout() method scheduled to be fired every 30seconds. Timeout is scheduled with Serializable object containing counter:

createTimer(Date initialExpiration, long intervalDuration, Serializable info)

Every time ejbTimeout is called, counter is increased. If it reach 3, then method which should be fired after 2 minutes is invoked, and also counter is set back to 0. It works as below:

ejbTimeout after 30sec (counter == 0): call A(); counter++;
ejbTimeout after 30sec (counter == 1): call A(); counter++;
ejbTimeout after 30sec (counter == 2): call A(); counter++;
ejbTimeout after 30sec (counter == 3): call A(); call B(); counter = 0;

Upvotes: 0

Brett Kail
Brett Kail

Reputation: 33946

There is no built-in way to order timers like that. You could do it manually:

  1. Schedule a single-action timer for A in 30 seconds with info=1
  2. Schedule an interval timer for B for 120 seconds
  3. When A fires with info=1, schedule a single-action timer for A in 30 seconds with info=2
  4. When A fires with info=2, schedule a single action timer for A in 30 seconds with info=3
  5. When A fires with info=3, don't reschedule
  6. When B fires, call A, then do the work for B. Schedule a single-action timer for A in 30 seconds with info=1

Upvotes: 1

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