Image Manipulation with ASP.NET 2.0

Configuring Http Handlers

Http Handlers must be configured in the web.config <httpHandlers> section. For example, ImageHandler is configured like this:

<httpHandlers>
  <add verb="*" 
     path="*.jpg" 
       type="ImageHandler"/>
</httpHandlers>

Additionally, IIS must have a mapping for the type of the files that the Http Handler serves up. Since ImageHandler processes JPEG files, there must be a mapping for .jpg files. By default, IIS has no .jpg file type mapping. After using the Internet Information Services GUI to configure the sample web site, right-click the web site and select Properties. Go to the Virtual Directory tab and press the Configuration button. Then add a mapping for the .jpg file type (Figure 2). Specify aspnet_isapi.dll for the executable. On my machine, this file is located in the C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727 folder. Specify .jpg in the Extension text box. Select All Verbs. Leave the "Script engine" and "Check that file exists" checkboxes checked. If the OK button stays disabled, you're experiencing an outrageous bug in the IIS configuration program. Click on the file path to enable the OK button.

Figure 2: Adding an extension mapping for an Http Handler.