IISASPNET

IISASPNET is the integration layer used to host ASP.NET applications in Microsoft Internet Information Services (IIS). It comprises the ASP.NET runtime, the request processing pipeline, and the configuration that connects IIS to the managed code executed by the .NET Framework or .NET runtime.

In IIS 6 and earlier, ASP.NET was enabled via the aspnet_isapi.dll ISAPI extension, which forwarded eligible requests to the ASP.NET runtime. With IIS 7 and later, the platform introduced an integrated pipeline, and ASP.NET runs within the IIS worker process (w3wp.exe) as part of the unified pipeline, allowing IIS modules and ASP.NET modules to cooperate during request processing. In IIS 7+ you enable ASP.NET support by installing the corresponding .NET Framework features, and requests are mapped automatically to the ASP.NET runtime for file types such as .aspx, .ashx, .asmx, and others.

The functionality includes dynamic compilation of pages, authentication, authorization, caching, session state, request validation, and error handling, as well as support for Web Forms, MVC, Web API, and other ASP.NET technologies. IISASPNET thus enables a wide range of server-side processing and web application patterns within IIS.

For ASP.NET Core applications, hosting in IIS uses a separate component called the ASP.NET Core Module (ANCM), which integrates with IIS to launch the Kestrel-based app; this is part of the broader IIS hosting ecosystem but is distinct from classic ASP.NET hosting via IISASPNET.

Management and configuration are performed via web.config and machine.config and through the IIS Manager, with application pools providing process isolation and resource control.