> -----Original Message-----
> From: Gero Vermaas [SMTP:[EMAIL PROTECTED]]
> Sent: Sunday, July 23, 2000 11:12 AM
> To: [EMAIL PROTECTED]
> Subject: Use DB constraints with EJB's or not?
>
> Hi,
>
> I had a discussion with a colleque of mine and we did not reach a
> agreement,
> maybe some experts on this mailing list can help us out....
>
> The question is: Should you use database level constraints to enforce the
> integrity of the database or is the integrity of the database the
> responsibility of the EJB?
[Van Luu] if you are proponent of ER and business logic in the data
tier then use database level contraints. Otherwise, enforced them on EJB.
> My collegues opinion is that it is the responsibility of the EJB to
> enforce
> the integrity of the data in the database. If you would implement this in
> constraints in the database then both the EJBs and the database would have
> to know about the integrity rules. Which is duplication of
> knowledge/logic,
> which is not a good thing.
[Van Luu] You can design EJB so that it can be deployed option of
using or not using the rules.
> At first I agreed with him, but now I have second thoughts:
> - What if the database is used by other (non J2EE) applications? The
> integrity then must be maintained by the database, or should all
> applications be held responsible for the integrity? The latter would mean
> distributing the reponsibility over multiple applications, which is not a
> good thing? This would advocate to put the responsibility in the database
> and define the constraints there.
[Van Luu] If your architecture allows other non-EJB app to use the
same database, then always enforce database integrity in the data tier.
> - By putting the constraints in the database you enforce that their is one
> place where the data is consistent. Specific application could add
> additional constraints for that application into their logic, as long as
> it
> does not conflict with the data model.
[Van Luu] When you deployed database with enforce integrity, then
turn the same rules off at the EJB-level at deployment time.
> I'm anxious to hear your opinions on this....
>
> Regards,
>
> Gero Vermaas
>
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