How to maintain the session throughout a transaction?

godhs · **Joined:** Mon May 16, 2005 4:40 am **Posts:** 5

Hello,

Could someone help me in handling this problem ?

Say a transaction involves 3 database calls and i need to commit the transaction only when all three database calls succeed without any exceptions. This means that i cannot create, commit and close a seperate session for each of these 3 calls. How do i maintain the session across the transaction.

thanks,
godhs

vgiguere · **Posted:** Sat May 21, 2005 2:45 pm

I can not find the article, but I remember reading that in Hibernate 3, when you set up you hibernate.cfg.xml file with your transaction factory set to JTATransaction and your transaction manager set to Weblogic or JBoss etc, the session factory would automatically attach any Session you request to the current ongoing transaction.

Code:

<property name="transaction.factory_class">org.hibernate.transaction.JTATransactionFactory</property>
<property name="hibernate.transaction.manager_lookup_class">org.hibernate.transaction.WeblogicTransactionManagerLookup</property>

If you can not have it to work, you can synchronize it yourself (which we did, but it's a lot of code) by implementing the javax.transaction.Synchronization interface and accessing your transaction manager with the following code:

Code:

private TransactionManager getTransactionManager()
{
    return (( SessionFactoryImplementor ) factory).getTransactionManager();
}

david · **Posted:** Sat May 21, 2005 6:15 pm

You can structure your code into layers.
Top layer is the Transaction use case, eg, doThreeOperations()
This is called from or is the call to a JTA CMT transaction method. If not using JTA then this is where you start and commit/rollback the transaction.

Then the next layer (DAO) has the various operations. eg

doThreeOperations() {
// TX started
try {
op1DAO.doOperation1();
op2DAO.doOperation2();
op3DAO.doOperation3();
}
catch(Exception e) {
doRollback();
}
// Tx Committed unless rollback hint provided.
}

All the DAO operations need is to call a utility class that provides the current session by using (and populating) a thread local. See WIKI for some code.
The thread local makes sure you get the same session for the current execution stream.