我有以下代码保存用户并发送jms消息。目前我正在 Package saveUserSendMessage 使用usertransaction。当事务嵌套时，我在ejb中得到一个异常。下面我该怎么做才能使嵌套事务成为可能？

@Resource(mappedName = "java:/JmsXA")
private static QueueConnectionFactory queueConnectionFactory;

@Resource(mappedName = "EjbQueueJndi")
private static Queue queueProp;

@PersistenceContext(unitName = "ejbPersistanceunit")
private EntityManager em;

@Resource
UserTransaction ut;

@Override
public boolean saveUserSendMessage(String name, String email, int age,
        boolean arg3) throws Exception {

    UserTransaction xact = ut;
    xact.begin();

    saveUser(name, email, age);
    sendMessage("Successfully saved the user");
    try {
        if (arg3)
            throw new Exception("Unsuccessfull");
        xact.commit();
    } catch (Exception e) {
        xact.rollback();
        throw e;
    }
    return true;
}

@Override
public boolean saveUser(String name, String email, int age)
        throws Exception {
    try {
        ut.begin();
        UserEntity ue = new UserEntity();
        ue.setAge(age);
        ue.setEmail(email);
        ue.setName(name);
        em.persist(ue);
        ut.commit();
    } catch (Exception e) {
        e.printStackTrace();
        throw e;
    }
    return true;
}

我得到一个例外：

15:51:04,127 ERROR [STDERR] javax.transaction.NotSupportedException: BaseTransaction.checkTransactionState - [com.arjuna
.ats.internal.jta.transaction.arjunacore.alreadyassociated] [com.arjuna.ats.internal.jta.transaction.arjunacore.alreadya
ssociated] thread is already associated with a transaction!