Commit transaction only if all EJB’s are successful

Question

I have a complex problem, but it can be exemplified by the following metaphor::

@Stateless
public interface ChildEJB01 {
    salvarGato(Gato g);
}

@Stateless
public interface ChildEJB01 {
    salvarCachorro(Cachorro c);
}

@Stateless
public interface ChildEJB01 {
    salvarPeriquito(Periquito p);
}

These three Ejbs are used in isolation at various points of my application and work well in isolation. But there’s a certain moment I need to use them together, see:

@Statefull
public class MasterEJB {

    @EJB
    private ChildEJB01 a;

    @EJB
    private ChildEJB02 b;

    @EJB
    private ChildEJB01 c;

    public void salvarTudo(){
        a.salvarGato();
        b.salvarCachorro();
        c.salvarPeriquito();
    }

}

Now I need to save all at once and I need everything to be saved in the database only if all are saved correctly [transaction].

Only that I have realized that even if one of them gives error what was done previously is saved anyway... How do I create a transaction for this method? (I’m using JTA (managed by Containner)).

My setup: Jboss AS7

---

editing for a new example using Ricardo’s tips

@Stateless
@TransactionManagement(TransactionManagementType.CONTAINER)
public class ChildEJB01 implements C01 {

@PersistenceContext
private EntityManager manager;

@WebMethod
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public void persist(String a){
    Model m = new Model();
    m.setDesc(getClass().getCanonicalName());

    manager.persist(m);
}

}

---

@Stateless
@TransactionManagement(TransactionManagementType.CONTAINER) 
public class ChildEJB02 implements C02 {

@PersistenceContext
private EntityManager manager;

@WebMethod
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public void persist(String a){
    Model m = new Model();
    m.setDesc(getClass().getCanonicalName());

    manager.persist(m);
}

}

---

@WebService
@Stateless
@TransactionManagement(TransactionManagementType.CONTAINER)
public class MasterEJB {

@EJB
private C01 c01;

@EJB
private C02 c02;

@Resource
private SessionContext contexto;

@TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
public void persist() {
    for (int i = 0; i < 3; i++) {
        c01.persist("");
        c02.persist("");

        if (i == 2) // forcando uma exceção apos 4 inserts
            throw new RuntimeException();
    }
}

}

SELECT IN THE BANK BEFORE RUNNING THE CODE:

mysql> SELECT * FROM test; Empty set (0.00 sec) mysql>

CONSOLE OUTPUT DURING CODE EXECUTION:

10:26:00,905 INFO [stdout] (http-0.0.0.0-8080-1) Hibernate: Insert into test (description) values (?)

10:26:01,006 INFO [stdout] (http-0.0.0.0-8080-1) Hibernate: Insert into test (description) values (?)

10:26:01,057 INFO [stdout] (http-0.0.0.0-8080-1) Hibernate: Insert into test (description) values (?)

10:26:01,101 INFO [stdout] (http-0.0.0-8080-1) Hibernate: Insert into test (description) values (?)

10:26:01,135 INFO [stdout] (http-0.0.0-8080-1) Hibernate: Insert into test (description) values (?)

10:26:01,168 INFO [stdout] (http-0.0.0.0-8080-1) Hibernate: Insert into test (description) values (?)

10:26:01,209 ERROR [org.jboss.ejb3.Invocation] (http-0.0.0.0-8080-1) JBAS014134: EJB Invocation failed on Component Masterejb for method public void implementations.MasterEJB.persist(): javax.ejb.Ejbexception: java.lang.Runtimeexception

SELECT AT THE BANK:

mysql> SELECT * FROM test;

+----+---------------------------+

| id | Description |

+----+---------------------------+

| 1 | implementations.Childejb01 |

| 2 | implementations.Childejb02 |

| 3 | implementations.Childejb01 |

| 4 | implementations.Childejb02 |

| 5 | implementations.Childejb01 |

| 6 | implementations.Childejb02 |

+----+---------------------------+

6 Rows in set (0.00 sec)

===

In short.. the rollback still does not work :(

== +1 Edit:

now using a UNICO EJB (without using other injected EJB’s);

@TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
public void persist() {

    for (int i = 0; i < 5; i++) {
        Model m = new Model();
        m.setDesc("KEKEKEKEKKE: " + i);
        manager.persist(m);
    }

    contexto.setRollbackOnly();
}

rollback was not done. ta VERY STRANGE :o

---

RESOLVED:

I had to activate the transactions for my DATASOURCE from JBOSS.. it was just mark the box: [x] USE JTA

Answer 1

Here we go! This will require a little knowledge on transactions and their propagation. In addition to enabling the use of JTA in persistence.xml.

Changing the persistence.xml

To enable transactions via JTA, should be specified in which datasource the transaction will occur as follows:

<jta-data-source>java:/meuDatasource</jta-data-source>

Writing down the EJB’s

Now, we need to note down the methods of the EJB’s children to support the spread TransactionAttributeType.REQUIRED. Does that mean that:

Transactionattributetype.REQUIRED: If there is already a transaction in progress, then that same transaction will be used. If there is no transaction in progress, then a new one will be created.

Let’s go to the codes:

Childejb1

@Stateless
public class ChildEJB1 {

    @TransactionAttribute(TransactionAttributeType.REQUIRED)
    public void salvarPiriquito() {
        //codigo
    }
}

Childejb2

@Stateless
public class ChildEJB2 {

    @TransactionAttribute(TransactionAttributeType.REQUIRED)
    public void salvarGato() {
        // codigo
    }
}

Childejb3:

@Stateless
public class ChildEJB3 {

    @TransactionAttribute(TransactionAttributeType.REQUIRED)
    public void salvarCachorro() {
        //codigo
    }
}

And finally, the Masterejb:

@Stateful
public class MasterEJB {

    private ChildEJB1 ejb1;
    private ChildEJB2 ejb2;
    private ChildEJB3 ejb3;

    @TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
    public void salvarTudo() {
        this.ejb1.salvarPiriquito();
        this.ejb2.salvarGato();
        this.ejb3.salvarCachorro();
    }
}

See that in Masterejb I used another type of transaction propagation (TransactionAttributeType.REQUIRES_NEW). What this kind of propagation tells us:

TransactionAttributeType.REQUIRES_NEW: This propagation must create a new transaction from a context without any transaction. If there is already a transaction in progress, then an error will be generated.

And what all this code posted means?

It means that when you call the EJB’s "children" methods in isolation, a new transaction will be created and the objects will be saved. I’m assuming that when these methods are called "alone", has no previously opened transaction.

When the methods of the EJB’s children are called by the method salvarTudo(), see that in the method itself salvarTudo() the transaction is already opened and that transaction propagates to the methods of the EJB’s son. If the transaction fails in any method of the EJB’s children, then the rollback will be done and no object will remain persisted from any EJB son.