Inside Technique : Online Registration and Validation with VB
By Scott Isaacs

When we wrote the InStockBot we wanted to create a reliable registration system. Our goal was to create a very simple solution for providing a demo version that can auto-upgrade itself to the full version plus limit piracy. We created InStockBot as a Visual Basic application that uses Microsoft's INet and WebBrowser custom controls. This application talks to ASP pages on our server.

We created a very simple database that tracks valid user ids. These ids can be as simple as an e-mail address or as complex as a combination of values (eg., random generator and person's name). Every time the application starts we call our server and validate the registration against the backend database. We are able to do this because our application requires an active internet connection.

Specifically, when the application starts up, we check if the application was ever registered on the current machine. If it is registered, we call our server to validate the user (this prevents any attempts to spoof with a random name). This validation is a simple request containing the user's personal identifier. If the validation succeeds, we start up the full-version of the program. If the validation fails, we open the registration screen to let the user register or run the demo version.

When the user registers, the same test occurs. We call the backend server and validate that the user identifier is valid. This has the added benefit of letting us track when user's who purchase the application first register it. In addition, we can track how many machines the application is registered on. This way, if we see a user id used to register many copies of the application we can do a piracy check and either disable or contact the user.

This approach is very effective for building applications and ensuring they are used properly. Next we explain how we built this in our InStockBot application.

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