OT2004 : Towards EJB 3.0

Despite the title, this session, led by Scott Crawford from the EJB expert group, turned out to be one of my favourites.

I’m a bit rusty on EJB. I was big into EJB for a few years and then one day I just stopped using it. I spent some time before the session reminding myself of the way of the EJB. Actually, EJB ain’t that bad.

This session was an opportunity to have our say about problems we see with EJB. Something we were clear on doing was focussing on the problems and consequences rather than “wouldn’t it be nice if…” solutions. Between us we came up with our top thirty gripes. In fact there were many more we could have come up with but didn’t have time.

From there we went through each of them and voted on whether we recognised the problem and, if so, whether it was deemed important. This narrowed it down to ten. Each of us then represented an issue close to our hearts and defended it in a debate with the goal to narrow it down to three.

The problem I represented was that EJBs only expose one coarse grained business interface to the outside world (ignoring the home/local/remote thing). This coarse grained API based exposes methods to clients (including other EJBs) that are not necessarily relevant. Objects (and EJBs) are different things to different people and by depending on the interface for the entire implementation, rather than a specific fine grained role, you end up with a higher coupling of components in the system and reduced flexibility. Most other APIs get this right but EJB prevents you.

Needless to say, I never made it into the top three. I had no chance against:

* Testability.
* Transparent persistence for entity beans.
* Death to RemoteException.

And to be fair, they are much more important :).

Some of the other things that made it into the top list (off the top of my head):

* More flexible O/R mapping, relations and finders.
* Breaking the 70’s paradigm shift of separating state and behaviour into entity and session beans. Whatever happened to OO?
* Simpler deployment.
* Declarative error handling.
* Lazy loading / pageable iterators in the specification.

Anyway, the results of this are to be fed back to the EJB group and I really hope they can make a difference. Time will tell.

Kudos to Scott for hosting a good session. Everyone came out feeling good about themselves. And well done to Robin Roos for being on best behaviour and not mentioning JDO once :). It was also reassuring to see the developers from BEA violently agreeing with all of our gripes – they too are victims!

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