Question

I have a web service (built using jaxb/jaxws) that invokes a stateless EJB to store some data in the database. The data is being stored as an entity bean. The entity bean has a unique constraint applied to it via the @Column(unique = true) annotation.

When the web service attempts to save data, the transaction fails, and rightfully so. The problem is that since I am using CMP, the transaction is not committed until after the call to the stateless EJB. The end result is that I am not able to trap the exception and it is getting funneled up to the WS stack and results in an ambiguous fault containing the string: Error committing transaction:;nested exception is: weblogic.transaction.internal.AppSetRollbackOnlyException.

Is there a way to catch the exception being thrown so I can provide more information to the caller? Thank you.

Version information:

• Application Server: Oracle Weblogic 10.3
• Persistence Provider: Hibernate 3.2.5.ga (JPA 1.0)
• JDK/JRE: 1.6_0_05 (provided by Weblogic install)

Update:
I tried to implement an EJB 3 interceptor around the method invocation and this does not appear to work.

public class TestInterceptor {

@AroundInvoke
public Object logCall(InvocationContext context) throws Exception {

    System.out.println("Invoking method: " + context.getMethod().getName());

    try {
        return context.proceed();
    } catch (Throwable t) {
        System.out.println("I caught an exception: " + t.getMessage());
        throw new Exception(t);
    }

}

The reason I think this doesn’t work is because the processing chain is such that the actual persist happens outside of the method (of course).

Answer 1

You could try using Bean Validation. It’s nicely connected with the JPA (invoked during pre-persist, pre-update and pre-remove phases and can be used in different layers of your application.

Unfortunately, as far as I know, if a validation constraint violation occurs, the transaction is marked for rollback… I don’t know how you could cope with that but one (seems nasty and untested) way I could think of is to inject a ValidatorFactory and validate the object by yourself. Perhaps then you could catch the ValidationException.

EDIT: I’m not sure if the Bean Validation was available in Java EE 5.

EDIT 2: You can create an interceptor which will catch the exception thrown by the JPA (or more precisely by the database). As the interceptor is invoked as a part of the same transaction as the EJB method you might need to explicitly invoke EntityManager#flush(-) to synchronise changes with the database.