Message Driven Bean -- Instance Creation..

Question

As we know MDB (inJMS) acts as a listener to a message coming from either a topic/queue. The instance of MDB is created by the EJB Container and the no. of instances created depend upon the corresponding values specified in the Deployment-Descriptor. So we never have to create instance of MDB bcoz container takes care of itself. MDB is eventDriven and the method onMessage is fired when topic/queue receives a message.
Now, can I have a scenario where my client creates an instance of MDB explicitly. Say I have an MDB by name TestMDB, I create an instance of MDB using new keyword something like the below code:
TestMDB testMDB = new TestMDB();
The client grabs messages which are recd. using onMessage of TestMDB. I put the msgs recd. in onMessage method into some kind of HashMap and return it to the client. This for sure satisfies my requirement, but EJB specification says MDB instances are created by the EJB Container itslef and that does not give me an easy feeling.
Are there any caveats of creating instances of Message Driven Bean ??

Answer 1

Hi,
Why would you like to create your own MDB instance?
Is it because you don�t want to use an EJB container?
Otherwise, you should know that the container is doing a lot of work under the cover. It is not that simple to achieved concurrent message processing.
I would really recommend you to either use an EJB container or to redesign your application. If you really don�t want to use a heavy weight EJB container you can have a look at Arjuna�MDS that provides you with a light weight container allowing to deploy MDBs like applications.
Hope this helps,
Arnaud
www.arjuna.com