IIS integration

As explained in ASP.NET Core in Action, 3e

UseIISIntegration is an ASP.NET Core extension method that configures an application for out-of-process hosting behind Internet Information Services.

IIS integration prepares an ASP.NET Core application to work with Internet Information Services. With out-of-process hosting, IIS acts as a reverse proxy: it forwards incoming requests to the application and returns the application’s responses. section 27.2.2

Choose the hosting integration that matches the IIS hosting model:

• UseIIS() configures in-process hosting, where IIS hosts the application directly inside the IIS process. section 27.2.2
• UseIISIntegration() configures out-of-process hosting, where the application runs separately behind IIS. section 27.2.2
• WebApplicationBuilder adds IIS integration automatically; custom application builders using HostBuilder must add the appropriate extension method explicitly. section 27.2.2
• The methods have no effect when the application is not hosted with IIS, so including them is safe in that situation. section 27.2.2

Custom builder with out-of-process IIS hosting

An application built with a custom HostBuilder can call UseIISIntegration() so the application and IIS negotiate the configuration required for out-of-process hosting. Applications created with WebApplicationBuilder normally need no additional call. section 27.2.2

A reverse proxy can change request details while forwarding traffic. ForwardedHeadersMiddleware uses headers such as X-Forwarded-For and X-Forwarded-Proto to restore the client address and original HTTP scheme; WebApplicationBuilder adds this middleware in a disabled state, enabled with ASPNETCORE_FORWARDEDHEADERS_ENABLED=true. section 27.3.2

Figure 27.8 The published application, using IIS as a reverse proxy listening at the URL http://localhost:81

The deployment arrangement shows IIS acting as a reverse proxy in front of the published application. section 27.2.2

How ASP.NET Core in Action, 3e covers it

How deep it goes

Explains hosting-model differences and forwarded-request behavior, but defers detailed IIS deployment configuration.

Examples

Uses UseIISIntegration(), UseIIS(), forwarded-header configuration, and an IIS reverse-proxy deployment arrangement.

What it assumes

Assumes basic ASP.NET Core application hosting and distinguishes WebApplicationBuilder from custom HostBuilder construction.

What you can do after

Operate/configure an ASP.NET Core application for IIS hosting and preserve forwarded request information.

How it connects

Connects IIS integration with reverse proxies, HostBuilder, WebApplicationBuilder, forwarded headers, and middleware.

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Related concepts

• ForwardedHeadersMiddlewareimplements · ForwardedHeadersMiddleware is ASP.NET Core middleware that applies proxy-forwarded HTTP headers to the request context.
• out-of-process hosting modelconfigures · An out-of-process hosting model runs an ASP.NET Core application in a separate process from IIS, which forwards requests to it.
• in-process hosting modelconfigures · An in-process hosting model runs an ASP.NET Core application directly inside the IIS process.
• WebApplicationBuilderused by · WebApplicationBuilder is an ASP.NET Core builder type that configures application services, hosting, logging, and related settings before constructing a WebApplication.

This explainer was generated by Manning's knowledge graph from the text of ASP.NET Core in Action, 3e. The section links point to the parts of the book it draws on.