I wrote this application in early 2002 to begin learning the .Net framework.  It maintains a SQL Server database containing  images that can each belong to an infinite number of categories. In this demo, it is being used as a Family Photo application but it could just as easily be used for categorization and retrieval of any kind of images such as a Real Estate or Used Car Search application that enables search by various attributes.

At the core of the application is the database and a single component that handles all update and retrieval. Various Windows Forms, ASPX Pages, and Web Services can communicate with the common database access component. The web portion of the application on the next page is almost trivial containing only about 135 lines of code (See the Code) - all of the functionality, power, and complexity of the application is at the common core. This is an example of three-tier design.  The code at the core would be identical for Family Photos, Real Estate Sales, Used Car Search, or any other such application.

Most of the time, it's a good idea to put as little code as possible in a Web Application and put the most functionality in central components and database stored procedures (but not always). 

It would be easy to develop a cell phone app or a Windows Forms app to do what this demo asp.net app does because just the GUI would change.

As an example of the advantage of 3-layer design, this web app was originally written, in 2002, in VB.Net using Framework 1.1. In 2005 I rewrote the 135 line presentation program in C# using Framework 2.0 to take advantage of new ASP.Net presentation features.  Nothing in the base component needed to change except for the connectionstring to a SQL Server 2005 database.  Now in 2006 I have again updated the GUI using the new ATLAS classes to provide AJAX capability to the picture selection and thumbnail display functionality.