> Think about two applications on the same back end. I delete a customer. How did your business tier handle this ?
> He must receive a message from the data tier, ok ?
> So who's handle it the data or the business tier ? :)

Well, if you do it this way, yes, but then you wouldn't do it the right way. :-)

You are never supposed to access the data directly, right? Otherwise, n-tier doesn't work to begin with.

Markus