Re: RM's Canonical database (was: Bob's 'Self-aggrandizing ignorant' Count)

Ron Jeffries wrote:
> On 3 Jul 2006 09:04:21 -0700, "Marshall" <marshall.spight_at_gmail.com> wrote:
>
> >> In favor of putting a common rule in the DBMS is that it is centralized. The
> >> "Once and Only Once", or "DRY" principle suggests that it should be there.
> >>
> >> Another possibility for a location for such a rule is in a middle tier, where it
> >> can also meet the DRY principle.
> >
> >But then you lose the centralization.
>
> Why do you think that? Rules can be centralized in the middle tier just as well
> as in the DB, can they not?

Well, I woud say not. Generally the dbms is designed for supporting multiple clients and multiple languages, and the middle tier isn't. (It's also the case that the dbms is designed for declarative expression of business rules, and the middle tier isn't.) Also the dbms interface is a programmable, meta-interface, capable of supporting whatever queries or updates may be required post hoc, whereas the middle tier just exports some API.

It is certainly *possible* to design your own meta-interface and support it in the middle tier, but that's a *lot* of work and doesn't happen in practice.

> Are you concerned about people going "around" the middle tier, perhaps? I'd
> think that could be obviated with some simple security measures, couldn't it?

It's certainly theoretically possible, but in practice this doesn't seem to
work. Not that it *couldn't* work, just that my experiece is that it doesn't. I suppose if I'd had some successes with that, I would feel differently.

Marshall Received on Tue Jul 04 2006 - 06:37:07 CEST