Question

We are refactoring a legacy application. The old code did something like this in a Controller method:

• Call DAO1.update()
• Call DAO2.update()

We’ve placed an in between a service layer, so the above code now looks like:

• Call Service1.update() –> Call DAO1.update()
• Call Service2.update() –> Call DAO2.update()

Each of the above two update methods have been marked transactional (using spring transactions). Old code didn’t handle transactions that well – now, we want a user action (controller method) to map only to a single transaction. How can we achieve that using spring transactions itself?

PS:

1. We did checked Hibernate’s Open Session in View pattern, but we
   would like a solution that makes use of Spring transactions – the
   above scenarios are not that common and we are worried about
   performance decay in OSIV pattern.
2. We can combine the two service methods above into a single method but would welcome a bit cleaner situation that won’t hinder reuse.

Answer 1

If you want to keep using the @Transactional annotation, then you sure have to wrap your calls in a broader, annotated method. So, either you define business services, which may become quite boilerplate/redundant indeed, or you make your controller’s handling method transactional itself (as a @Component it is a Spring-managed bean so you can use @Transactional there too), or you define a flexible, generic, callback-based template:

@Component
public class TxWorker {
    @Transactional
    public <T> T doInTx(Callable<T> callback) throws Exception {
        return callback.call();
    }
}

The drawback of the latter is that it may become a bit messy if you overuse it.

Note that you may combine the OpenSessionInView pattern and Spring-managed transactions, since the Hibernate session (or JPA entityManager) may span across many tx (see What is the difference between Transaction-scoped Persistence context and Extended Persistence context?). But its main goal is to provide lazy-loading while rendering views, so it is not exactly what you’re looking for.