But the question is -- if your base home returned a heterogenous collection of EJB's, how would you know which subclass to downcast each instance to? You could try to use instanceof with the remote interfaces, but that gets nasty. Or, you could have some sort of "discriminator" attribute, but that gets nasty too.
There are two basic ways of handling inheritance in database mappings; either you have all attributes in all subclasses drawn from a single table (with a discriminator column added in) and then do separate SELECT statements, or you use what is called "root-leaf" mapping, where the base class maps to a customer "root" table and the subclasses's unique attributes map to "leaf" tables tha share the same primary key with the root table.
The issue is that neither of these approaches is supported by the Entity model. Therefore, unless you happen to be lucky and work in an environment like WebSphere Studio where this can be handled for you,
you should just avoid the issue. Don't use Entity beans here. Use DAO's and do it yourself.
Alternatively, this could be handled in EJB 2.0 with dependent objects -- If you're using the approach of storing all attributes in a single table, then you could have different dependent objects for each subtype.
The fact is that EJB's, even Entity EJB's are not domain objects. They are database wrappers. Admit that, and often the problems become more understandable.
Kyle
