Walter,

Not one word of what you said has anything to do with N-Tier. You can build an N-tier system design in VFP today and then simply replace the UI tier sometime later with an HTML layer and you will have an internet application. The whole idea of N-Tier is that I don't have to know what I might want later on any tier in order to build a functioning app today that will be able to be enhanced later for expected and unexpected requests.

By isolating responsibilities into discrete tiers today, I can easily swap any tier for a different implementation of that behavior in the future without any requirement that I even touch the other tiers. This technology exists right now, it is NOT rocket science, it is not the bleeding edge. It is simply a better way to architect systems than the monolithic design architecture.

N-tier does require some planning of the system ahead of time before the coding begins. This is called design. In order to accomplish the design one must know what the requiremetns of the system will be, this is called analysis. Of course we can skip the analysis and design phases of the project and build the app from the seat of our pants, but we will get exactly what we built, a seat of our pants application. Over time it will become a "held together with chewing gum and spit application" as we fix each problem encountered which then ripples through with other problems due to the fix.

Why does the monolithic application end up a mess? Because there is no clear deliniation of responsibility within the components of the application. Code gets spread around in various places and it becomes a nightmare to fix anything that is wrong simply because it is difficult to impossible to find all the places that are affected.

N-tier architecture requires that responsibilities are clerly defined for each component, and that no component steps outside its area of responsibility. Therefore if there is a problem you go to the component that is responsible for that behavior and fix it. If you later decide that you would like access to the data from Excel, you make an Excel sheet with macros that use the same business objects to access data that your VFP UI does. All the rules are enforced, any changes you make to the business objects will affect both UI's. Now you want Inet access, you make an HTML UI that uses the same business objects that the other two use, etc. etc. etc.

The key to N-tier design is Programming to interface and not implementation.