The different hosting models in ASP.NET Core

 Let’s explore the different hosting models in ASP.NET Core and the .NET Core Hosting Bundle:

1. In-Process Hosting (IIS Express):

   • In this model, the ASP.NET Core application runs within the same process as the IIS worker process (w3wp.exe).
   • Advantages:
     • Performance: Since the application shares the same process, there’s less overhead in communication between the web server and the application.
     • Integration with IIS: You can leverage IIS features like authentication, authorization, and URL rewriting.
   • Considerations:
     • Scalability: In-process hosting is not suitable for high-scalability scenarios because each request ties up an IIS worker thread.
     • Isolation: If the application crashes, it affects the entire IIS worker process.
   • Use Case: Suitable for development and debugging with IIS Express.

2. Out-of-Process Hosting (Kestrel):

   • In this model, the ASP.NET Core application runs in a separate process from the web server (e.g., Kestrel).
   • Advantages:
     • Scalability: Kestrel is lightweight and designed for high concurrency. It can handle many simultaneous connections.
     • Isolation: If the application crashes, only the Kestrel process is affected.
     • Cross-Platform: Kestrel can run on Windows, Linux, and macOS.
   • Considerations:
     • Security: Kestrel doesn’t have built-in features like authentication or SSL. It’s recommended to use a reverse proxy (e.g., Nginx or IIS) in front of Kestrel.
     • Integration with IIS: You can still use IIS as a reverse proxy for load balancing or SSL termination.
   • Use Case: Suitable for production deployments.

3. .NET Core Hosting Bundle:

   • The .NET Core Hosting Bundle is an installer that includes the .NET Core Runtime and the ASP.NET Core Module.
   • Purpose: It allows ASP.NET Core apps to run with IIS.
   • Installation Order: If installed before IIS, the bundle installation must be repaired after IIS installation.
   • Direct Download: You can download the installer directly from the official page.
   • Visual C++ Redistributable: On older Windows versions, install the Visual Studio C++ 2015, 2017, or 2019 Redistributable.
   • Parameters: You can customize the installation using parameters (e.g., skip installing ASP.NET Core Module or runtime components).
   • Compatibility: The ASP.NET Core Module is forward and backward compatible with supported .NET Core releases.