Re: BMP relationships

>
> Now, I would implement this so that the relationship fields
> (Cd.artist and
> Artist.cds) are lazy loaded.

This implies that you're not caching anything. Transaction isolation
comes into play here as well. These are important details when
considering stale-data scenarios.

> Calling set() -methods would
> update both the object and the parameter object, ie.
> bornInTheUsa.setArtist
> (bruceSpringsteen) would update both bornInTheUsa.artist
> field AND bruceSpringsteen.cds collection (otherwise
> bruceSpringsteen will have invalid state after the call).

Not necessarily. It would have an invalid state after the
transaction finishes, if it's not voted that it should rollback. I
mention this so that you're aware that in other methods within the
same TX the inserted relationship *may* not show.
Again, TX isolation comes into play as well.

>
> Is this the right way to go? Plus, can I trust that in
> clustered environment also EJB's in other instances are
> updated?
> So that there is not an invalid artist bean in some
> instance having bruceSpringsteen.cds missing the bornInTheUsa?

As long as you don't cache the entities(and make sure the container
doesn't do it for you either), yes you can trust.
As a sidenote, I'd monitor performance if there's no caching at all.

Bear in mind that CD artists don't release CDs all that often. You could
still enable caching and either:
A) Set a conservative timeout on cached instances (say, an hour).
B) Have some manual cache-flush facility somewhere. It doesn't sound
good, but works like a charm, performance-wise.

My 2c,

JP

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