>>User Interface Layer
>>Input/Output Layer
>>Business Layer
>>Data Services (Access) Layer
>>Database Layer
>
>I'm afraid I have to disagree with you, oJim! ;-)
>
>I don't agree that what you discribe above is 5-tier architecture. It's 5-layer architecture which is substantially different from 5-tier architecture. The user interface layer and the i/o layer represent the front end in this case, and the database services layer together with the database layer really is the data tier. One can introduce lots of more layers without really creating new tiers.

Marcus,

You could be correct in some situations and incorrect in others. For example what if the UI is VB or HTML and the IO is VFP running on another machine? In my opinion tier and layer are almost synomonous with very slight differences.