How To Use Entity Beans

To EB or not to EB, that is the question...

What say we tear into this discussion? What are entity beans? When do they add value? What becomes of plain old DomainObjects? What are the comparative merits and demerits of the following usage styles?

Three general ways to use them identified to date seem to be:

• EntityBeansAsDomainObjects
• EntityBeansAsDomainObjectGraphs
• EntityBeansAsDataGateways

And one specialized way, attributed to DaveMuirhead. Does anyone else HaveThisPattern?

• SearchResultAsEntityBean

See also: IbmSanFrancisco

--RandyStafford

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I am not sure I have seen SearchResultAsEntityBean, but there was a thread a while back on EJB-INTEREST proclaiming the merits of EntityBeans that represent collection rather than instances. There is even an EJB Container which has optimized for this (Egypt I think).

I does seem strange given that an EjbHome and its EjbBean are already sort of a virtual collection of EjbBean's, where each EjbBean's PrimaryKey is its unique identifier in the EjbHome.

--ChrisRaber

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The problem is that you can't write the 'batch' operations in the Home, which seems natural.

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That's not strictly true. With EjbTwo you get EjbHome methods which can work on multiple beans in much the same way that static methods could work on multiple (or all) the instances of an object.