ASP.NET Core Hosting on IIS on Windows

This article will provide details about how to deploy ASP.NET Core web application or Web API on IIS. .NET Core 2.2 onwards there were significant changes in the hosting model to IIS. Prior to .NET Core 2.2 only option available was to use IIS as a reverse proxy to ASP.NET Core Kestrel web server.

With .NET Core 2.2 option was added for direct in-process hosting to IIS which can improve the performance significantly. The old approach with IIS as a reverse proxy is also available as an out-of-process hosting model. ASP.NET Core hosting on IIS supports two models for hosting on the IIS i.e. In-process hosting model & out-of-process hosting model.

ASP.NET Core Hosting on IIS is different as compared to ASP.NET Webforms or ASP.NET MVC.

Supported operating systems

  • Windows 7 or later
  • Windows server 2012 R2 or later

Apps published for 32 bit (x86) and 64 bit (x64) are supported. Application pools under should be configured accordingly for 32-bit & 64-bit apps.

Type of Hosting Models

ASP.NET Core Hosting on IIS
In-process hosting model

As the name suggests ASP.NET Core application runs in the same process as IIS (w3wp.exe) and it does not use the Kestrel web server. This hosting model uses IISHttpServer that is hosted directly inside the application pool. This hosting model provides a significant performance improvement over the other out-of-process model as it does not have to forward requests to Kestrel for processing. IIS handles process management in the traditional way with the help of windows process activation service (WAS).

Request flow details:

  • Request arrives from web at HTTP.sys
  • HTTP.sys routes the request to IIS
  • ASP.NET Core module receives the request and passes it to IIS HTTP Server.
  • IISHTTPServer passes the request to ASP.NET Core middleware pipeline.
  • ASP.NET Core application handles the request and returns response
Out-of-process hosting model

Again as the name suggests here ASP.NET Core application runs in a separate process from the IIS worker process. This is similar to what was available in ASP.NET Core versions prior to 2.2. ASP.NET Core module handles process management, this module is responsible for starting the ASP.NET Core App when the first request arrives & also restarts if it shuts down or crashes.

Here IIS acts as a reverse proxy to Kestrel web server where ASP.NET Core application is running. For application to be configured as an out-of-process model it needs to specify UseIISIntegration as part of WebHostBuilder code in the program.cs file. ASP.NET Core module doesn’t support HTTPS forwarding.

Steps for ASP.NET Core hosting on IIS

  • Publish your application
  • Install/Enable IIS Server on windows
  • Install the .NET Core Hosting Bundle
  • Create a new application pool & website for your application
Publish your Application

Right click on project in Solution Explorer and select Publish option. This should being up the screen to publish your code. Select Folder option to publish all the files to a folder. This folder will be configured in IIS as website folder.

IIS Configuration

Use the Add Roles & Features wizard to Enable IIS on Windows server operating system.

IIS Installation

Select following services under web server on Select role services screen

IIS Installation Select Services

For windows desktop operating system select Control Panel ==> Program ==> Program & Features ==> Turn windows features on or off and select following features for installations

IIS Installation on Windows Desktop

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Install .NET Hosting Bundle

You can download the required version of the hosting bundle from here. The hosting bundle installs the .NET Core Runtime, .NET Core Library, and the ASP.NET Core Module.

If the Hosting Bundle is installed before IIS, the bundle installation must be repaired. Run the Hosting Bundle installer again after installing IIS.

Create IIS Site

Open IIS Manager & expand server node in connections panel on left hand side. Right click site folder and select “Add Website…” from the context menu. Provide Site name, Physical path (where code was published), binding configuration details & click on ok.

IIS Create Website

Finally browse and check your website.

Summary

ASP.NET Core hosting on IIS supports two models for hosting on the IIS i.e. In-process hosting model & out-of-process hosting model. .NET Core 2.2 onward there were significant changes in the hosting model to IIS.

In-process hosting model provides a significant performance improvement over the other out-of-process model as it does not have to forward requests to Kestrel for processing

References: https://docs.microsoft.com/en-us/aspnet/core/host-and-deploy/iis/?view=aspnetcore-3.1

You can also check my other Article on Configuring multiple ASP.NET Core hosting environment: https://procodeguide.com/programming/asp-net-core-hosting-environment/

Hope you found this article useful
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