I am writing some persistence classes for our database and I was given the direction to create interfaces for each entity in the DB then create implementation classes. This seems wrong, and in my opinion you would create abstract classes for entity objects like AbstractPerson instead of interfaces. Does it really make a difference if you create interfaces like PersionIntf and then implement that or extend an Abstract class? I'm curious if there are any best practices for ORM mapping when it comes to writing persistence. Thanks