JTA or LOCAL transactions in JPA2+Hibernate 3.6.0?

Question

We are in the process of re-thinking our tech stack and below are our choices (We can\'t live without Spring and Hibernate due to the complexity etc of the app). We are also mov

Answer 1

As Duffy already mentioned, JTA is not synonymous with 2 phase commit, which is something done via the XA protocol.

In JBoss AS for example, you can explicitly choose whether you want a given data source to be an xa-datasource or a tx-datasource. In both cases, transactions are managed via JTA.

In some cases you might already have been using JTA without knowing it. If you send a JMS message transactionally, or update a transactional cache in the same transaction where you modify something in a database, the transaction manager automatically switches to XA mode. The datasource representing your DB may not be XA, but in an XA transaction 1 resource is allowed to be non-XA. Updates to this resource then happens via the last resource commit optimization.

Although you should always calculate the risks and test for your self, I do want to warn against unfounded fear. XA seems to be one of those things we as developers have been brought up to fear. There was an interesting discussion on the JBoss forum about this recently: when to use xa-datasource.

The thing is that XA might have been a complex technology with sub-par implementations in the past, but almost a decade and a half since this FUD this might not be the case anymore. What was complex big enterprise stuff in 1995 is your common run of the mill technology in 2011.

Compare this with the fear we were once brought up with for EJB, which is now completely irrelevant anymore, or the fear for virtual machines (obviously not a problem for Java programmers), or when you're really participating in this industry for a long time, the fear for doing something as basic as function calls ;)

Answer 2

JTA doesn't mean two phase commits. I think it's the combination of JTA and XA drivers that makes two phase commits possible.

I'd still recommend using JTA and declarative transactions over embedding transaction logic in code. Transactions are best done in aspect oriented fashion, a la Spring.

UPDATE:

With the additional information you've posted, I agree with your argument. I'd recommend using Spring declarative transactions and the HibernateTransactionManager class.