Re: Can I put the business logic in Servlets and bypass EJB?

Tom Anderson <>
Tue, 20 May 2008 19:20:27 +0100
On Tue, 20 May 2008, jmDesktop wrote:

The more I read from I find that EJB are not favored by many. And it's
not something I want to do unless I have to anyway. Is it somehow wrong
to to put my business logic in my servlet or a javabean and not use
Enterprise JavaBeans at all? That still looks like good separation to
me. I think it's MVC, but not sure.

The business logic should be in business objects. Those can be EJBs, but
they can also be plain old java objects (POJOs). In the latter case, they
would be created and manipulated directly by the servlet, within its own
process, rather than living in a separate process or container as EJBs
would. So, the answer to your question is definitely no, it's not wrong.

The advantage of EJBs over POJOs is that you get transactionality,
lifecycle management, persistence, distribution and searchability for free
(although TANSTAAFL). However, if you don't need those things (and man,
perhaps most, people don't), then they bring you no benefits. And, since
they're more work to write, configure, and execute, they're a net loss.

I think a sensible engineering decision would be to apply the You Aren't
Gonna Need It rule, and build your system with POJOs for now. However, try
to structure it so that a transition to EJBs later, if you decide to make
one, would be as painless as possible. That's pretty simple: define your
business objects with interfaces, and manipulate them exclusively through
those, and encapsulate creation of business objects (including searching
the database to make them) in a factory object (possibly using the Facade
pattern to hide a bunch of classes which do the creation work behind a
simple interface).

Then, if you want to go EJB, all you have to do is upgrade the interfaces
to EJB interfaces, fix up your client code to deal with RemoteExceptions
all over the place, and rewrite the factory object to use the EJB finders.
Oh, and then implement the actual EJBs. But at least the changes to the
servlet will be minimal.

Huge caveat: i did a lot of work with EJBs, but quite a while ago -
specifically, before EJB 3, which i understand has changed things a lot.
Like, there are no entity beans any more, so all the above advice is
worthless. Eh. Maybe it still applies to session beans.

If you don't get a good answer on this topic here, i suggest trying The
Server Side:

Which certainly used to be a really good place for this kind of
discussion. Don't know if it still is!


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