I have been using WebSphere for a while. In the IBM world, when you have a foreign key relationship in the database schema, you have to map a ejb-relationship to the foreign key. The information is kept in ibm extension xml file. As the EJB specification 1.1 doesn't really cover EJB-relationship implementation. Using the EJB relationship makes your code unportable in my opinion. Hope people who are using other application servers can shed some light on this.