how to force instantiation of MDBs when JBoss starts up?

[Csk Kumar]

Hi,
I am implementing an event handler using MDB and i am using jboss-5.1.0.GA. In my case, whenever jboss starts up my MDB (constructor should be called) should get instantiated , so that whenever message comes to the queue my onMessage() method will be invoked for message processing. In my MDB constructor i am doining instantiation of other required classes for message processing.

Issue:
But now the issue is my MDB constructor is getting called only after the message comes to the queue, becuase of this my message processing(onMessage call) is getting delayed.
Could you please tell me how to instantiate pool of MDB's when JBoss starts up?

Thanks in advance!!

My MDB code looks like this:
EventHandlerMDB.java

[color=blue][/color][color=blue][/color]
@MessageDriven(mappedName = "MyQueue", activationConfig = {
		@ActivationConfigProperty(propertyName = "destinationType", propertyValue = "javax.jms.Queue"),
		@ActivationConfigProperty(propertyName = "destination", propertyValue = "MyQueue") })
@Pool(value=PoolDefaults.POOL_IMPLEMENTATION_STRICTMAX, maxSize=50, timeout=10000)	
public class EventHandlerMDB implements MessageListener {
                private OperatorDao operatorDaoObj=null;
	private RatingInfoDao ratingInfoDaoObj=null;
	private DfSubscriberDao dfSubsDaoObj =null;

public EventHandlerMDB() {
         operatorDaoObj =new OperatorDao();
         ratingInfoDaoObj=new RatingInfoDao();
         dfSubsDaoObj = new DfSubscriberDao();
}

public void onMessage(Message message) {
        ds.setOperatorDaoObj(operatorDaoObj);
        ds.setRatingInfoDaoObj(ratingInfoDaoObj); 
        ds.setDfSubsDaoObj(dfSubsDaoObj);

        try {
	if (message != null) {
	        /*Check the message whether it is a object message*/
	      if (message instanceof ObjectMessage) {
	          ObjectMessage objMsg = (ObjectMessage) message; 
                          ..........
                          ...................
                      }
}.......	

Queue configuration in Jboss looks like this:destinations-service.xml

<?xml version="1.0" encoding="UTF-8"?>

<server>

   <!--
      The Default Dead Letter Queue. This destination is a dependency of an EJB MDB container.
   -->
   <mbean code="org.jboss.jms.server.destination.QueueService"
      name="jboss.messaging.destination:service=Queue,name=DLQ"
      xmbean-dd="xmdesc/Queue-xmbean.xml">
      <depends optional-attribute-name="ServerPeer">jboss.messaging:service=ServerPeer</depends>
      <depends>jboss.messaging:service=PostOffice</depends>
   </mbean>
   
   <!--
      The Default Expiry Queue.
   -->

   <mbean code="org.jboss.jms.server.destination.QueueService"
      name="jboss.messaging.destination:service=Queue,name=ExpiryQueue"
      xmbean-dd="xmdesc/Queue-xmbean.xml">
      <depends optional-attribute-name="ServerPeer">jboss.messaging:service=ServerPeer</depends>
      <depends>jboss.messaging:service=PostOffice</depends>
   </mbean>   

   <!-- Queue defined for Eventhabdler MDB -->
  	<mbean code="org.jboss.jms.server.destination.QueueService" 
		name="jboss.messaging.destination:service=Queue,name=MyQueue" 
		xmbean-dd="xmdesc/Queue-xmbean.xml">  
		<depends optional-attribute-name="ServerPeer">jboss.messaging:service=ServerPeer</depends>  
		<depends>jboss.messaging:service=PostOffice</depends>  
		<attribute name="JNDIName">MyQueue</attribute>  
		<attribute name="RedeliveryDelay">10000</attribute>  
		<attribute name="MaxDeliveryAttempts">3</attribute>  
	</mbean> 

</server>

[Peter Johnson]

There is no configuration option to do this, so the typical way is to create a startup service and have it feed some dummy messages to the queue. This might help you get started:
http://community.jboss.org/wiki/ExampleHelloWorldService

[Csk Kumar]

Hi,
Thanks for the reply. It was really hepfull.
As you said now I am sending dummy messages to the queue during jboss startup and it is working fine .