ASP.NET in a Nutshell

Chapter 6. User Controls and Custom Server Controls

Reuse is a technique that is important to most developers. Reuse allows you to avoid constantly reinventing the wheel by using functionality that has already been built and tested. It increases productivity, by reducing the total amount of code you need to write, and reliability, since by using tested code, you (presumably) already know the code works reliably.

ASP.NET provides a range of options for reuse. The first is the wide variety of built-in server controls that ship with ASP.NET. These server controls alone can eliminate hundreds, or even thousands, of lines of code that needed to be written to achieve the same effect in classic ASP. In addition, the .NET Framework Class Library (FCL) provides hundreds of classes to perform actions (such as sending SMTP email or making network calls) that in classic ASP would have required purchasing a third-party component or making calls into the Win32 API.

Going hand-in-hand with reuse is the concept of extensibility, the ability to take the existing functionality provided by the .NET Framework and ASP.NET and extend it to perform actions that are more tailored to your particular applications and problem domains. ASP.NET provides a significant number of avenues for extensibility:

Custom server controls

Allow you to create entirely new controls for use with ASP.NET or to derive from existing controls and extend or modify their functionality.

Components

As in classic ASP, components ...