Modules in IIS 7

Configuring Modules in IIS 7
Applies To: Windows 7, Windows Server 2008, Windows Server 2008 R2, Windows Vista

The IIS 7 extensibility model lets you develop and deploy Web server components, named modules , as either native DLLs that use native C++ APIs or managed types developed by using ASP.NET APIs. Web server modules can be either of the following types:

• Native modules (native .dll files): These files are also named unmanaged modules , because they are not created by using the ASP.NET model. By default, most of the features included in the Web server are implemented as native modules.
• Managed modules (managed types created by .NET assemblies): These modules are created by using the ASP.NET model.

Modules process parts of a request to provide a desired service, such as authentication or compression. This process is similar to the manner that Internet Server API (ISAPI) filters work. Typically, modules do not generate responses to clients; instead, handlers perform this action because they are better suited for processing specific requests for specific resources. For more information about how to configure handlers, see Configuring Handler Mappings in IIS 7 .

• Native modules are loaded when a Web server worker process is initialized. These modules can provide services—for example, authentication or compression—for a site or an application.
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  For security reasons, native modules are registered or unregistered only at the Web server level by the server administrator. However, you can enable or remove registered native modules at the site or application level.
  
• Managed modules can be configured separately for each site or application. They are loaded for processing only when this is required by that site or application.