EJB3 Getting at original JDBC Errors

Question

Hi all,

I am using EJB3 on Glassfish using the default TopLink persistance manager. Within a Session Bean, when the persistence manager catches a DB exception, it marks the transaction to be rolled back, and throws an EJBException, in turn wrapping a RollbackException. Now I was expecting to be able to get the original jdbc exception out of the caused by exception of one of these exceptions, but it is not.

It is important that I do retrieve the original exception, as I need to report back to the users what the problem is, and to do this I need to analyse the SQL error codes.

Does anyone know if it is possible to get this information from Toplink? Or whether Hibernate makes it possible?

Thanks,

Answer 1

Good question, Ant

I know you want to throw a database exception but when it occurs the application, in most of the time, is not able to restore its initial state or it does not know how to recover from it. So it should be handled as a runtime exception. Some problems in database exceptions includes

• database connection failure
• query is wrong
• table or column does not exist

Above you see the application is not be able to restore its initial state. If you think it is possible restore its initial state so you should use a application exception. Client will get the same application exception thrown by your business method. If you want to be able to get the exact exception thrown by your business method you have two choices:

• Use a business delegate pattern to access your EJB

As you know, runtime exception is wrapped by a EJBException, so you shold use something like

Let's suppose you have this Stateless session bean

@Stateless
public class BeanImpl implements Bean {

    public void doSomething() {

        try {
            // some code
        } catch(SomeException e) {
            throw new EJBException(e);
        }

    }        

}

So you wrap your session bean through a business delegate

public class BeamBusinessDelegate implements Bean {

    // your stateless session bean goes here
    private Bean bean;

    public BeamImpl() {
        InitialContext i = new InitialContext();

        bean = (Bean) i.lookup(<GLOBAL_JNDI_ADDRESS_OR_RELATIVE_ENVIRONMENT_NAMING_CONTEXT_ADDRESS>);
    }

    public void doSomething() {
        try {
            bean.doSomething()
        } catch(EJBException e) {
            throw e.getCause();
        }
    }
}

Or you can extends EJBException according to your needs

public class DatabaseException extends EJBException {

}

So in your business method

@Stateless
public class BeanImpl implements Bean {

    public void doSomething() {

        try {
            // some code
        } catch(SomeException e) {
            throw new DatabaseException();
        }

    }        

}

regards,

Answer 2

I had the same issue. I ended up using the AroundInvoke interceptor method , that way you can catch any exception on the server side , and extract whatever info you want to and wrap it to throw your own exception , and set the EjbContext to rollback the transaction.

I can provide you with an example if you don't come right.

Answer 3

The only way I've found to do what I want, is to force the manager to write to the db using manager.flush(), and then catch the PersistenceException that that throws. I can then log the database error as I want, and throw an EJBException to force rollback. Leaving the container to do the flush seems to irretrievably lose any useful messages with TopLink.

Answer 4

Hello,

I have the same question : how to get the SQL error message generated from JPA?

I haven't found the solution either but, I added this line in my persistence.xml

 <properties>
  <property name="toplink.logging.level" value="FINE" />
 </properties>

and now, I can see the sql commands issued.

Reference : http://www.jairrillo.com/blog/2008/09/04/introduction-to-jpa-part-1-getting-started/