Scheduling a MDB

Question

I'm looking for a way to schedule a MDB. My requirement is that the MDB is set to feed a system from the company. This system goes out for maintenance every night, but the other systems don't know about it and may keep trying to feed it. A persistent queue is great in the way that my messages could be pilled until system goes back online.

How could I manage that? I've run into that already: schedule a message driven bean to access a queue during certain times? but it uses java 7, and worst, message is lost if the server restarts (messages is taken out of the JMS Queue and kept in memory until timer process it).

Another use of this would be to implement a "retry" queue. In case of error I want to retry processing my message, but not immediately, after a certain amount time only.

Any ideas to keep my MDB offline for a certain amount of time?

Answer 1

Well, it looks like there is no way to pause a MDB in a generic way. The best solution is, like most people will answer, to use the DLQ (or DMQ).

Now, if I want to introduce a timer on a message, I set the time to live of the producer to the amount of time I want the message to wait. Then I send it to a normal queue, lets say waitingQueue which has no consumer. After expiration, the message is sent to default destination (mq.sys.dmq for Glassfish MQ, make sure to create a jms resource with mq.sys.dmq as imqDestinationName). I have a MDB listening to the error queue and responsible of sending the message again. Now, if I want to "close" a queue for some time, when a message arrives in the queue, I check if current time is allowed or not. Just set the time to live to the amount of time before next opening hours and send it to waitingQueue.

The reason I didn't use it since the beginning is that I fell into a few pitfalls. Here are a few useful properties to set when using DMQ with Glassfish 3.1.1 and its embedded MQ.

imq.message.expiration.interval=1 that's for the poll interval on each queue before sending timed out messages to the DMQ. Default is 60 seconds. If like me you want to test your application with little latency, this is what you need.

Answer 2

Most versions of JBoss publish a management MBean that allows you to stop delivery on a MDB. If you're using EJB3, however, they auto-start, so you will need to register a startup class to stop starting MDBs at boot time if boots occur in your MDB's blackout period. Once past that snafu, you can schedule a simple quartz job to start and stop the MDBs according to your delivery windows.