When will I use the setRollbackOnly() method ? 1

[thelordoftherings]

Hello,

I am a bit confused.
Can someonle please explain me when will I use the setRollbackOnly() method of an EntityContext? What is the case that I will need to state that the only possible outcome of the transaction is to roll back the transaction? And if it is rolled back why creating it at first place?

 

[timw]

When you want the EJB Container to rollback the transaction (assuming Container Managed Transactions). You would normally stop whatever process you're doing and exit the method when you set this, because any further activity, say to an Entity Bean, will cause the container to complain.

Tim
---------------------------
"Your morbid fear of losing,
destroys the lives you're using." - Ozzy

 

[thelordoftherings]

But the setRollBackOnly will do a rollback no matter what, so why create a transaction if it is marked as rolled back...?

 

[timw]

If you're using CMT then the container will create the transaction for you. The setRollBackOnly() informs the container that it should rollback that transaction when the operation exits.

Tim
---------------------------
"Your morbid fear of losing,
destroys the lives you're using." - Ozzy

 

[thelordoftherings]

But gain: a rollback cancel the transaction, why creating a transaction and then cancel it no matter what?

 

[timw]

You only call setRollbackOnly if something you're doing fails ( maybe the operation cannot be completed because a resource is missing or something blew up and you caught a checked exception ). In this case, you know you can't go on, so you tell the container it can roll the transaction back.

Tim
---------------------------
"Your morbid fear of losing,
destroys the lives you're using." - Ozzy

 

[thelordoftherings]

Oh so I will normally put it in an exception catch block. Am I correct?

 

[timw]

99% of the time, that's where it is used (in my code at least).

There's always the chance that tests done in normal code will flag the case that you cannot proceed, so you could call it there. But usually as a result of catching an exception.

Tim
---------------------------
"Your morbid fear of losing,
destroys the lives you're using." - Ozzy

 

[thelordoftherings]

Now it's much clearer, 10x Tim