Hi, I have the following problem: I have a MDB (EJB 3.0 on AS: 4.0.5.GA) that consumes messages from a queue. In the onMessage method I am calling the method of a Stateless Session Bean (injected with SEAM-mechanism).
public void onMessage( Message msg )
{
// extract userId and type from msg - both string variable
try{
this.requestManager.insert(userId, type) // stateless session bean injected with seam
catch ( JMSException e ){
e.printStackTrace();
}
}
The insert Method is as follows:
public void insertPemRequest( String userId, String type )
{
Person person = new Person( userId, type );
try
{
this.entityManager.persist( examRequest );
this.entityManager.flush();
// create business process in jbpm
}
catch ( ConstraintViolationException exp ){
// do nothing, i.e do not kick off new business process
}
catch ( EntityExistsException entityEx ) {
// do nothing, i.e do not kick off new business process
}
}
The Person Bean has unique constraint on userId and type: i.e:
@Entity
@Table( uniqueConstraints= {@UniqueConstraint(columnNames={"userId", "type"}) } )
public class Person {
// ---- getter/setter for id, name, type
}
By catching the EntityExistsException I want to avoid that a business process is kicked off twice for the same person and type. As there might be many messages send and consumed in parallel all requesting to kick off a business process for one person and type combination - this is a good way to control that a business process is kicked off once and once only for a name/type combination.
Now my problem: The message is still redelivered and send to the DLQ, altough I caught the EntityExistsException. All other exceptions should lead to sending the message to DLQ. But not the EntityExistsException as this is a "tolerated" exception. I know from FAQ
What type of Exceptions should an MDB throw?
The quick answer is none.
But I am catching the exception. right? Or is this correct behaviour and I have to change my design that no EntityExistsException is thrown?
