Hi,
I am really questioning the usage of a DAO layer in a J2EE app where you have also a business service layer and a ORM solution. DAO's main purpose is to shield developers from the SQL ,seperate the logic and the data. So when using hibernate or whatsoever, you are duplicating nearly the same code.

Yes, a good ORM solution is essentially a superset of a DAO framework. I cant think of many situations where you would want or need to layer an ORM ontop of DAO.
Sometimes an ORM is used as a DAO layer e.g. using hibernate or toplink behind entity beans I but realy dont see the point of doing that either because all good ORMs provide a cleaner more powerful and less intrusive API than entity beans.

Some IBM shops use entity beans ontop of DAOs to unify data access between widely different data sources such as CICS mainframes and RBDs but other than that DAO layers tend to used directly by the business service layer rather than behind an object model.

One of the reasons for using a DAO layer is that it maps leverages the underlying store characteristics (e.g. RDBMS join/query/batch-update) to directly perform business operations in a higly optimal manner, and you obviously lose all that if you go via another layer first. A modern ORM solutions like hibernate can do alot of that as well though with all the aditional benefits of exposing the data as a fully featured domain model.

Paul.