Transaction Context and Persistance context

[asdf kumar]

Hi Team, as my knowledge in ejb persistence, if i am using transaction scoped persistence context, the persistence context is propagated to other ejb calls also under same transaction. For example, If I have called EJB2 from EJB1(under transaction1) the same transaction and persistence context is propagated to EJB2 and if any change is made to the managed entity inside EJB2, it will be reflected to the database after transaction completion.

But in the mentioned code, I have to do EntityManager.merge on managed entity "studBean". Kindly help me to clarify my understanding.

@Stateless
@RemoteBinding(jndiBinding = "EJB3BeanRemote")
@LocalBinding(jndiBinding = "EJB3BeanLocal")
public class CalculatorBean implements CalculatorRemote, CalculatorLocal {

	@PersistenceContext(unitName="StudentPU")	
	private EntityManager em;
	
	@EJB
	private StudProcessor studProcessor;
	
	@TransactionAttribute(TransactionAttributeType.REQUIRED)
	public int addStudent(int roll, String name){
		Student stud = em.find(Student.class,1);
                  //if I modify the attribute 'name'
                 stud.setName("Avinash 123");
                 //and  after the method returns, transaction will be over and changes will be synchronized with the data base.

                //above works well. now i will do the name attribute change of "stud" managed bean inside another EJB
                
                 studProcessor.modifyName(stud);
		return stud.getRoll();
	}
}

@Stateless
@RemoteBinding(jndiBinding = "StudentBeanRemote")
public class StudProcessorBean implements StudProcessor {
	
	@PersistenceContext(unitName="StudentPU")	
	private EntityManager em;
	@Override
	@TransactionAttribute(TransactionAttributeType.REQUIRED)
	
           public void modifyName(Student studBean) {
		studBean.setName("Avinash 123");
		 //my assumption was that i need not call merge since the persistence context is provided through "CalculatorBean"
                // and with the return from this method, studBean will autometically be synchronized with the database.
                //but without calling merge, it is not getting synchronized.
                 em.merge(studBean);
		
	}
}

I am calling "StudProcessorBean " bean inside "CalculatorBean" through injection. As per my understanding, the "modifyName()" method should not use merge. But without this call, Student bean is not synchronised with the data base. Kindly help me.