EJB 3.0 – Nested Transaction != Requires New

ejb-3.0jakarta-eenested-transactionstransactions

I just read the Transactions Chapter (10) of "Mastering EJB 3.0" and now I'm confused about nested transactions.

The book says

"The EJB-defined transaction manager does not
support nested transactions; it requires support for only flat transactions." (Site 278, Note)

This fact is described not only by this book, I found this statement in other books / websites.

But if I call a "Requires New" annotated Method from a, let's say "Required" annotated Methode, what I have is a nested transaction, isn't it? I can roll back the inner transaction or commit it, without affecting the outer transaction.
And if I want the outer Transaction to be aborted, I throw an EJBException back and the whole transaction will be rolled back.

So is it just that this behavior is not required by the EJB 3.0 specification or have i misunderstood something? I just can't get the difference between nested transactions and the described behavior.

Regards
Norman

Best Answer

RequiresNew does not create a nested transaction because the first transaction is suspended while the second transaction is running. A nested transaction looks like this:

Nested transaction example
> method1 - begin tran1
  > method2 - begin tran2
    workA
  < method2 - commit tran2
< method1 - rollback tran1 (tran2 also rolled back because it's nested)

Instead, RequiresNew looks like this:

EJB RequiresNew example
> method1 - begin tran1
  > method2 - suspend tran1, begin tran2
    workA
  < method2 - commit tran2, resume tran1
< method1 - rollback tran1 (tran2 remains committed)

Related Solutions

Java – Implementing support for nested transactions using JDBC 3.0

There could be dependencies in the code that expect the commit to be done rather than deferred (for example, if the isolation level is set to TRANSACTION_READ_COMMITTED).

Consider fixing your transaction manager to do the nested transaction on a separate connection.

UPDATE: It looks like the Spring framework uses SavePoints to provide nested transactions. My guess is that they just ignore the issue of isolation mode.

C# – SqlException from Entity Framework – New transaction is not allowed because there are other threads running in the session

After much pulling out of hair I discovered that the foreach loops were the culprits. What needs to happen is to call EF but return it into an IList<T> of that target type then loop on the IList<T>.

Example:

IList<Client> clientList = from a in _dbFeed.Client.Include("Auto") select a;
foreach (RivWorks.Model.NegotiationAutos.Client client in clientList)
{
   var companyFeedDetailList = from a in _dbRiv.AutoNegotiationDetails where a.ClientID == client.ClientID select a;
    // ...
}

Best Answer

Related Solutions

Java – Implementing support for nested transactions using JDBC 3.0

C# – SqlException from Entity Framework – New transaction is not allowed because there are other threads running in the session

Related Topic