I'd like to get JTA/EJB-like "join-existing-transaction" semantics in the simple case (sharing a single conn to the same DB, one-phase commit only) in Tomcat without having to dump more JARs in common/lib (e.g., JOTM) or migrate to Spring framework just yet. The default JDBCTransaction does not support this, and I was wondering if there is a solution floating around before reinventing the wheel.

We have code that looks like this:



We want to avoid the default JDBCTransaction behavior, where tx2.commit() in B() will call connection.commit() on the underlying JDBC connection right away, preventing the outer transaction from being able to roll back properly. Has anyone had any luck with a lightweight solution for this, like introducing a ThreadLocal or similar into JDBCTransaction?

You can put the Hibernate Transaction in a ThreadLocal and begin/commit/rollback in a Servlet filter. A good place to do that is the HibernateUtil class from the reference documentation.

We'd like to keep transaction scope minimized to the business method/service where it's active, rather than keeping a transaction open through the presentation layer/rendering phase. Is that possible?

Would it be reasonable to make my own Transaction like JDBCTransaction, that keeps a ThreadLocal to indicate whether a transaction was already in progress? beginTransaction and commit would become no-ops unless you're at the top level. rollback() would set a flag like UserTransaction.setRollbackOnly does. then top-level commit() either commits or rolls back depending on the rollbackOnly flag.

Has anyone done anything like that?

This is really trivial: First, use the Hibernate Transaction API to keep your code portable. Then, use a ThreadLocal to hold the Transaction object for the current thread. Begin and commit whenever you like by calling static methods on that ThreadLocal utility class. Just have a look at HibernateUtil and try to understand how it handles the Session, its pretty much the same for Transaction.