Java EE (Java Enterprise Edition) General Discussion

Hi!

I have extensive EJB model (entities with many child entities, entities with association to other large (many fields, BLOBs including) entities, and so on) and I would like for each JPA query configure what properties or associated entities (actually - in arbitrary depth) of selected entities should be fetched.

E.g. for one query I would like to fetch only Order (and no data of associated entities), but for other queries I would like to fetch Order, Order.Customer, Order.ShippingAddress.ZipCode and nothing else ( e.g. if there is Ordere.Route, Order.Billing and other associations, then I would like not to waste resources for fetching them). In both case the select clause of query can include only Order, but the results should be different - i.e. - there is no associated data in the first case and there are some associated data the second case.

I know that one solution is to declare all associations as lazy and then - after reading the result of query - do some touching for retrieving the associated data:
String check = order.Customer.toString();
check = order.ShippingAddess.ZipCode.toString();

But I see 2 problems with this: 1) it is not nice (resources are wasted for simply touching associated entities); 2) I assume that each "touch" operation generates other query to database that could be executed together with the original query. So - it would be nice to configure JPA query somehow to let it know which associations will be required from the result and which not.

What is the best practice?

I found, that JBoss server has lazy-loading-group configuration, but - I guess - it is JBoss specific:
http://docs.redhat.com/docs/en-US/JBoss_Enterprise_Application_Platform/4.2/html/Server_Configuration_Guide/Loading_Process-Lazy_loading_Process.html
besides - it is XML and it would be more pretty if query configuration could be done with annotations!