ejb question from sun

[Timber Lee]

What type of enterprise bean is used to embody business objects?
A. javax.ejb.EnterpriseBean
B. java.rmi.Remote
C. javax.ejb.SessionBean
D. javax.ejb.EntityBean
its answer is D, but the business logics are also contained in stateless bean.

[Thomas Hofmann]

SBs are mainly used as control (worflow) objects. EBs provide an OO view (business objects) of data in (relational)database.

[Timber Lee]

it is to expensive for entity bean to perform business logic.

[Thomas Hofmann]

Sure, the usage of an entity bean as business object is more expensive than a plain java object, because an entity bean provides TX and security (and distibution [remote EBs])features. But according to your question entity beans are used as business objects and session beans for control logic -> session facade pattern.