CDI & JPA: Best scope for repository classes

Question

I'm wondering what would be the most efficient (in terms of needed resources) scope for a repository class in CDI. Imagine the following scenario:

@RequestScoped
//OR @ApplicationScoped OR @SessionScoped OR @ConversationScoped?
public class SomeRepository{
  @Inject 
  private EntityManager em;

  public SomeClass getSomeClassById(int id){
    return em.createNamedQuery("getSomeClassById",SomeClass.class).
             setParameter("id",id).getSingleResult();
   }
}

The EntityManager in ths example is produced with a @RequestScoped scope.

Answer 1

Interesting question I think. Unexpectedly I can't think of anything that makes these classes special. So I would make them @ApplicationScoped as a new instance would function exactly the same as the one I just discarded. Not sure it would have any noticeable impact on the heap, probably not but maybe if they had to be recreated a lot?

I think it's fine to go with what conceptually feels more right for you.