Lazy/Eager loading strategies in remoting cases (JPA)

Question

I\'m running into LazyLoading exceptions like the most people who try remoting with an ORM. In most cases switching to eager fetching solves the problem (Lazy Loading / Non

Answer 1

1. You can get rid of all collections whatsoever and use NamedQueries instead. We used this approach in one project (EJB + Swing), and it worked pretty well - thus you determine exact data to be fetched. NamedQueries are normal queries, imagine them as PreparedStatement-s. The idea is not to create/retreive/update/delete single objects with queries. The idea is that you fetch your Collections with queries. For example, instead of mapping a @ManyToMany List, define a NamedQuery that fetches that list. Thus you can fetch the collection data separately, and only whenever you need it, not automatically.

2. Use a custom Proxy (using CGLIB) for transferred objects - whenever a collection is referenced (via its getter), attempt retreival, and catch any LazyInitializationException and make a call to the server tier for the data requested.

3. Just as the previous one, but make proxies only of the collections, in the way Hibernate proxies them when lazy initialization is needed.

4. Also, take a look at the Value List Handler pattern - might be useful.

(You can also use hibernate.max_fetch_depth (if using Hibernate) with a combination of the above, if it is suitable for your case.)