Walter,

>> Note: I'll use N-tier by the meaning of at least 3-tier.

Sure, the 'N-Tier' designation is just a simple acknowledgement that there _could_ be more than 3.

>> Well the N-tier theory is definately not new, If its going to play a very
>> important role in the future I still doubt. Of course there is much to gain
>> when it comes to flexibility, but i still doubt what advantages it will give
>> the user. If designing a N-tier system is only more work and doesn't give the
>> user any usable advantages, well skipp it !!

It gives the user an advantage in that it gives you, the developer, a real potential boost in your productivity. That way you can provide them with more robust, longer lasting solutions.

I think a part of the resurgance of interest in this type of approach is due to a few things. Here's a couple I can think of:

1) The recent popularity of the Internet. It's just a big network really.

2) The software that's matured enough to make this worthwhile. Remember before COM, COM+, DCOM & DCOM+ the solution was dial-up and private networks. Same process, different (older) tools.

>> Well I still doubt if it's the right way in all cases.

Agreed. If your business case doesn't warrant it then you're absolutely correct. I've found few that could not benefit in some fashion though.

>> Well of course this another issue. The main problem i'm struggling with is a
>> clear definition of N-tier and how it should be implemented. IOW the subject
>> is too vague for me. I personnally think N-tier is only a piece of the
>> client/server theory and there is no accepted standard yet how N-tier
>> applications should be implemented.

Ahh.. Here's a simple look.

Divide your application into three parts; 1) Data, 2) Business Logic and 3) User Interface.

It's really that simple.

I think the part that confuses people is the Business Logic part. My definition would start with this: Business Logic is that part of an application that does something *TO* the data.

The Data part would then be defined as that part of an application that is *WHERE* we do something with the data once we're done doing something _TO_ it.

The User Interface is *HOW* we do something with _TO_ data.

As far as _how_ to implement them, if by that you mean what product is best for what part, then sure, but that question will IMO *never* be answered. *g*

HTH

Best,