What is the difference between a session and a transaction in JPA 2.0?

Question

I just begin my JPA 2.0 studies, and I have this piece of code:

em = SessionFactory.startSession();
tx = em.getTransaction();

My problem is

Answer 1

In Hibernate, the transaction management is quite standard, just remember any exceptions thrown by Hibernate are FATAL, you have to roll back the transaction and close the current session immediately.

Here’s a Hibernate transaction template :

    Session session = null;
    Transaction tx = null;

    try{
        session = HibernateUtil.getSessionFactory().openSession();
        tx = session.beginTransaction();
        tx.setTimeout(5);

        //doSomething(session);

        tx.commit();


    }catch(RuntimeException e){
        try{
            tx.rollback();
        }catch(RuntimeException rbe){
            log.error("Couldn’t roll back transaction", rbe);
        }
        throw e;
    }finally{
        if(session!=null){
            session.close();
        }
    }