Abstracting Object Persistence

How can I abstract the implementation of my object persistance.

For example, I want to create a layer/service that will return references to persistant objects irrespective of how they are implemented e.g. EJB, Object-Oriented database, or simple Data Access Objects.

Otherwise, I will have to decide on persistance implementation before I start the design.

Alternatively, is it possible to map EJB's to Object-Oriented Database?

[462 byte] By [jaco@cyberseal.co.za] at [2007-9-26 6:03:39]