3.15 Web User Controls and Web Custom Controls

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If you need to build an application using server-based controls, but none of those provided in ASP.NET are suitable, it is possible to create your own. Web user controls are generally easier to build than custom controls, but are more difficult to use since they cannot be added to the Visual Studio toolbox; instead, they are represented as a default icon or glyph when they are placed on a form. This provides a maintenance problem since the components cannot be shared, and each developer using them needs to have a copy of the control installed locally.

Web custom controls must be written in code, but they can then be added to the toolbox and used like any other control. In addition, the control can be placed in the global assembly cache and shared between applications.

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