Custom ASP.NET controls overview

The ASP.NET controls in the Toolbox task pane are the controls provided by the Microsoft .NET Framework Versions 2.0 and 3.5. At times, you might need functionality in a control that is not provided by the built-in ASP.NET controls. In those cases, you can use a custom ASP.NET control created by a developer or a third party software vendor.

You can use custom controls developed by others, such as those featured in the Control Gallery on the Microsoft ASP.NET website, or create custom controls by using a visual design tool such as Microsoft Visual Studio.


There are potential security risks when using and developing custom ASP.NET controls. For more information, see Securing Custom Server Controls in the MSDN library.

Working with custom ASP.NET controls

To work with a custom ASP.NET control in Microsoft Expression Web, you need to do three things:

  1. Make the custom control available to Expression Web. To do this you can add the custom control's assembly to your website's bin folder or install the custom control into the Global Assembly Cache (GAC) on both your computer and your web server. For information, see Add a custom ASP.NET control to a website.

  2. Reference the custom control in your page or website. To do this you can either add a register directive in the pages you want to use the control or specify the tag prefix and namespace mapping in your website's web.config file. For information, see Reference a custom ASP.NET control.

  3. Add the custom control to the Code view of your page. For information, see Add a custom ASP.NET control to a page.

Support for custom ASP.NET controls

Once you've completed the steps under Working with Custom ASP.NET Server Controls, Expression Web provides virtually the same support for your custom ASP.NET control as is provided for the default set of ASP.NET controls. The only exception is custom ASP.NET controls don't appear in the Toolbox task pane or on the Insert menu; Expression Web provides the following for custom ASP.NET controls:

  • ASP.NET IntelliSense and syntax checking in the Code view of your page

  • Property editing in the Tag Properties task pane

  • Preview in the Design view of your page

  • Common Tasks smart tag menu in Design view

  • ASP.NET error messages in Design view

For information about adding a custom control to a web page, see Add a custom ASP.NET control to a page.

See also


Add a custom ASP.NET control to a website

Reference a custom ASP.NET control

Add a custom ASP.NET control to a page