Problem with rollback in EJB and CMT

Question

Hello,
I faced a problem in my application that I really do not understand (but I really would like to). How can I trigger a rollback of a transaction that is container-managed (CMT)? I know that any system exceptions are supposed to be handled by the container automatically and will cause a transaction rollback when they are thrown from an enterprise bean method. My Problem now is that I'm unable to make this work in my application.
Consider a situation like this:
The ManageEntityBean holds a simple save() method that creates an instance of EntityA and another of EntityB. Both instances store an arbitrary number (here 10). After this, the entityManger (injected from the container) is asked to make these instances persistent. EntityB is mapped with a "unique" constraint, so any attempt to store the same number twice will cause an SQL Exception.
First time when the save() method is invoked, the instances aEntity and bEntity are made permanent in the database. Second time when the save() method is invoked, the database throws an exception because bEntity is violating the unique constraint. What I would expect now is a complete rollback of the whole transaction. Instead, only bEntity has not been made permanent, but aEntity has.
What's wrong with this code?
@Stateless
public class ManageEntityBean implements ManageEntity {
     @PersistenceContext
     private EntityManager entityManager;
     @TransactionAttribute(TransactionAttributeType.REQUIRED)
     public void save() {
          try {
               EntityA aEntity = new EntityA(10);
               EntityB bEntity = new EntityB(10);
                entityManager.persist(aEntity);
                entityManager.persist(bEntity);
          } catch (Exception e) {
               throw new EJBException(e);
@Entity
public class EntityA implements java.io.Serializable {
     @Id
     @GeneratedValue
     private long     id;
        @Column(name="NUMBER")
        private int   number;
     public EntityA() {}
     public EntityA(int number) {
          this.number = number;
@Entity
public class EntityB implements java.io.Serializable {
     @Id
     @GeneratedValue
     private long     id;
     @Column(name = "NUMBER", unique = true)
     private int          number;
     public EntityB() {}
     public EntityB(int number) {
          this.number = number;
}I found two related topics in this forum but still I didn't find the solution yet.
[Enterprise JavaBeans - CMT and JDBC|http://forums.sun.com/thread.jspa?forumID=13&threadID=525651]
and
[ Forums - A CMT Session Bean Does Not Maintain the Transaction Correctly| http://forums.sun.com/thread.jspa?forumID=13&threadID=161512]
Maybe anyone can give me a hint. Help is very much appreciated
Christoph

Answer 1

Thank you for your input!
The save() method is simply invoked from the test applications main() method:
public class Test {
     public static void main(String[] args) {
          JndiUtil<ManageEntity> jndiUtil = new JndiUtil<ManageEntity>();
          ManageEntity handler = jndiUtil.lookupBeanContext("ManageEntityBean", ManageEntity.class);
          handler.save();
}Btw. I use Hibernate as persistence provider and JBoss 4.2.2.GA as application server.
For clarity I attach some lines of the debug logging that is produced when the test application is getting started for the second time:
### open Session
17:44:00,555 DEBUG *[SessionImpl] opened session at timestamp: 5007498610909184*
17:44:00,555 DEBUG [AbstractEntityManagerImpl] Looking for a JTA transaction to join
17:44:00,555 DEBUG [JDBCContext] successfully registered Synchronization
17:44:00,555 DEBUG [AbstractEntityManagerImpl] Looking for a JTA transaction to join
17:44:00,555 DEBUG [AbstractEntityManagerImpl] Transaction already joined
### invoke em.persist(aEntity)
17:44:00,555 DEBUG [AbstractSaveEventListener] executing identity-insert immediately
17:44:00,555 DEBUG [AbstractBatcher] about to open PreparedStatement (open PreparedStatements: 0, globally: 0)
17:44:00,555 DEBUG *[ConnectionManager] opening JDBC connection*
17:44:00,555 DEBUG [SQL]
/* insert de.zippus.domain.EntityA
17:44:00,556 INFO [STDOUT] Hibernate:
/* insert de.zippus.domain.EntityA
17:44:00,558 DEBUG [IdentifierGeneratorFactory] Natively generated identity: 2
17:44:00,559 DEBUG [AbstractBatcher] about to close PreparedStatement (open PreparedStatements: 1, globally: 1)
17:44:00,559 DEBUG [ConnectionManager] aggressively releasing JDBC connection
17:44:00,559 DEBUG [ConnectionManager] releasing JDBC connection [ (open PreparedStatements: 0, globally: 0) (open ResultSets: 0, globally: >0)]
### invoke em.persist(bEntity)
17:44:00,559 DEBUG [AbstractSaveEventListener] executing identity-insert immediately
17:44:00,559 DEBUG [AbstractBatcher] about to open PreparedStatement (open PreparedStatements: 0, globally: 0)
17:44:00,559 DEBUG [ConnectionManager] opening JDBC connection
17:44:00,559 DEBUG [SQL]
/* insert de.zippus.domain.EntityB
17:44:00,560 INFO [STDOUT] Hibernate:
/* insert de.zippus.domain.EntityB
17:44:00,561 DEBUG [AbstractBatcher] about to close PreparedStatement (open PreparedStatements: 1, globally: 1)
17:44:00,561 DEBUG [ConnectionManager] aggressively releasing JDBC connection
17:44:00,561 DEBUG [ConnectionManager] releasing JDBC connection [ (open PreparedStatements: 0, globally: 0) (open ResultSets: 0, globally: >0)]
17:44:00,561 DEBUG [JDBCExceptionReporter] could not insert: [de.zippus.domain.EntityB] [* insert de.zippus.domain.EntityB */ insert into >ENTITY_B (NUMBER) values (?)]
com.mysql.jdbc.exceptions.MySQLIntegrityConstraintViolationException: Duplicate entry '10' for key 2
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:931)
17:44:00,563 WARN [JDBCExceptionReporter] SQL Error: 1062, SQLState: 23000
17:44:00,563 ERROR [JDBCExceptionReporter] Duplicate entry '10' for key 2
17:44:00,563 DEBUG [AbstractEntityManagerImpl] mark transaction for rollback
17:44:00,563 ERROR [ManageEntityBean] Caught exception: javax.persistence.EntityExistsException: >org.hibernate.exception.ConstraintViolationException: could not insert: [de.zippus.domain.EntityB]
17:44:00,563 ERROR [ManageEntityBean] Exception Cause: org.hibernate.exception.ConstraintViolationException: could not insert: >[de.zippus.domain.EntityB]
17:44:00,564 DEBUG *[ManagedEntityManagerFactory] ************** closing entity managersession *************** Up to now I'm not that experienced in reading and understanding this kind of logging, but what I can see is, that there is a transaction that spans the whole unit of work and that this transaction is marked for rollback. I think that's quite a good thing, isn't it?
But what really puzzles me here is, that both calls of em.persist() result in an opening of a jdbc connection and an immidiate execution of a database insert. Tell me if I'm wrong, but is this really the right place to happen?
For what reason soever hibernate thinks it has to make these instances permanent, no matter if there is already a session that is taking care of this. If so, I might deal with a wrong hibernate configuration, I checked, but I can't find anything..
What do you think?
Thanks in advance!
Christoph