EJB3 Transaction Propagation

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隐瞒了意图╮
隐瞒了意图╮ 2020-12-13 04:25

I have a stateless bean something like:

@Stateless
public class MyStatelessBean implements MyStatelessLocal, MyStatelessRemote {
    @PersistenceContext(unit         


        
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  • 2020-12-13 05:20

    Matt, the question you ask is a pretty classic one, I think the self-reference solution by Herval/Pascal is neat. There is a more general solution not mentioned here.

    This is a case for EJB "user" transactions. Since you are in a session bean you can get the user transaction from the session context. Here's how your code will look with user transactions:

    // supposing processObjects defined on MyStatelessRemote1 and process defined on MyStatelessLocal1
    @Stateless
    @TransationAttribute(TransactionAttributeType.NOT_SUPPORTED)
    public class MyStatelessBean1 implements MyStatelessLocal1, MyStatelessRemote1 {
    
        @Resource
        private SessionContext ctx;
    
        @EJB
        private MyStatelessLocal1 myBean2;
    
        public void processObjects(List<Object> objs) {
            // this method just processes the data; no need for a transaction
            for(Object obj : objs) {
                this.myBean2.process(obj);
            }
        }
    
    
        public void process(Object obj) {
    
            UserTransaction tx = ctx.getUserTransaction();
    
            tx.begin();
    
            // do some work with obj that must be in the scope of a transaction
    
            this.mgr.merge(obj);
            // ...
            this.mgr.merge(obj);
            // ...
            this.mgr.flush();
    
            tx.commit();
        }
    }
    
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  • 2020-12-13 05:26

    I think has to do with the @TransationAttribute(TransactionAttributeType.Never) on method processObjects.

    TransactionAttributeType.Never

    http://docs.sun.com/app/docs/doc/819-3669/6n5sg7cm3?a=view

    If the client is running within a transaction and invokes the enterprise bean’s method, the container throws a RemoteException. If the client is not associated with a transaction, the container does not start a new transaction before running the method.

    I assume that you are client the method processObjects from the client code. Because probably your client is not associated with a transaction the method call with TransactionAttributeType.Never is happy in the first place. Then you call the process method from processObjects that altough having the TransactionAttributeType.Required annotation was not a bean method call and the transaction policy is not enforced. When you call merge you get the exception because you are still not associated with a transaction.

    Try using TransactionAttributeType.Required for both bean methods to see if it does the trick.

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