The entity bean should have data and methods that directly work on that data. The session bean glues together entity beans with business logic that spans entity beans.

Of course, they also tell you to use session beans and direct database logic as well. Entity beans are the most ridiculously complex, useless bit of junk I've seen in a while. Three interfaces for each bean! And they don't even relate to each other except through the xml bindings! It's garbage.