IL Code, CLR and .NET evolution (.NET 6)

As far as I know, codes written in any .NET language can not be executed without CLR.

Please take this code

public static void Main(string[] args)
{
    var builder = WebApplication.CreateBuilder(args);
    builder.Services.AddControllersWithViews();
    using var app = builder.Build();
    app.UseStaticFiles();
    app.UseRouting();
    app.UseEndpoints(endpoints =>
    {
        endpoints.MapDefaultControllerRoute();
    });
    app.Run();
}

The documentation says CreateBuilder adds an IServer instance by calling the UseIIS method to boot the CoreCLR and host the app inside of the IIS worker process (w3wp.exe or iisexpress.exe).

I can not understand a bit how the CLR can be started from the Main() method. Then Who is converting this Main() IL to machine code?

Or am I missing something?

So, what i think is

HTTP.sys----->IIS--->AspNetCoreModule---> aspnetcorev2_inprocess.dll ---->hostfxr--->find and

start CLR and call manged Main()---->CreateBuilder()---->UseIIS()----->It just tells the CLR to host the app inside w3wp.exe.

So, booting the CLR basically means hosting the app inside the w3wp process and not re-starting the CLR.

Please correct me, if I am not getting the point. for reference, details of UseIIS()

public static IWebHostBuilder UseIIS(this IWebHostBuilder hostBuilder)
{
if (hostBuilder == null)
{
throw new ArgumentNullException(nameof(hostBuilder));
}

// Check if in process
if (OperatingSystem.IsWindows() && NativeMethods.IsAspNetCoreModuleLoaded())
{
var iisConfigData = NativeMethods.HttpGetApplicationProperties();
// Trim trailing slash to be consistent with other servers
var contentRoot = iisConfigData.pwzFullApplicationPath.TrimEnd(Path.DirectorySeparatorChar);
hostBuilder.UseContentRoot(contentRoot);
return hostBuilder.ConfigureServices(
services =>
{
services.AddSingleton(new IISNativeApplication(new NativeSafeHandle(iisConfigData.pNativeApplication)));
services.AddSingleton();
services.AddTransient();
services.AddSingleton(new IISServerSetupFilter(iisConfigData.pwzVirtualApplicationPath));
services.AddAuthenticationCore();
services.AddSingleton(_ => new ServerIntegratedAuth()
{
IsEnabled = iisConfigData.fWindowsAuthEnabled || iisConfigData.fBasicAuthEnabled,
AuthenticationScheme = IISServerDefaults.AuthenticationScheme
});
services.Configure(
options =>
{
options.ServerAddresses = iisConfigData.pwzBindings.Split(new[] { ';' }, StringSplitOptions.RemoveEmptyEntries);
options.ForwardWindowsAuthentication = iisConfigData.fWindowsAuthEnabled || iisConfigData.fBasicAuthEnabled;
options.MaxRequestBodySize = iisConfigData.maxRequestBodySize;
options.IisMaxRequestSizeLimit = iisConfigData.maxRequestBodySize;
}
);
});
}

return hostBuilder;
}
}

1 Reply

Know the answer? Post it — somebody with the same question will find it here.

Sachin Singh4y ago
So, what i think is

HTTP.sys----->IIS--->AspNetCoreModule---> aspnetcorev2_inprocess.dll ---->hostfxr--->find and

start CLR and call manged Main()---->CreateBuilder()---->UseIIS()----->It just tells the CLR to host the app inside w3wp.exe.

So, booting the CLR basically means hosting the app inside the w3wp process and not re-starting the CLR.

Please correct me, if I am not getting the point. for reference, details of UseIIS()

public static IWebHostBuilder UseIIS(this IWebHostBuilder hostBuilder)
{
if (hostBuilder == null)
{
throw new ArgumentNullException(nameof(hostBuilder));
}

// Check if in process
if (OperatingSystem.IsWindows() && NativeMethods.IsAspNetCoreModuleLoaded())
{
var iisConfigData = NativeMethods.HttpGetApplicationProperties();
// Trim trailing slash to be consistent with other servers
var contentRoot = iisConfigData.pwzFullApplicationPath.TrimEnd(Path.DirectorySeparatorChar);
hostBuilder.UseContentRoot(contentRoot);
return hostBuilder.ConfigureServices(
services =>
{
services.AddSingleton(new IISNativeApplication(new NativeSafeHandle(iisConfigData.pNativeApplication)));
services.AddSingleton();
services.AddTransient();
services.AddSingleton(new IISServerSetupFilter(iisConfigData.pwzVirtualApplicationPath));
services.AddAuthenticationCore();
services.AddSingleton(_ => new ServerIntegratedAuth()
{
IsEnabled = iisConfigData.fWindowsAuthEnabled || iisConfigData.fBasicAuthEnabled,
AuthenticationScheme = IISServerDefaults.AuthenticationScheme
});
services.Configure(
options =>
{
options.ServerAddresses = iisConfigData.pwzBindings.Split(new[] { ';' }, StringSplitOptions.RemoveEmptyEntries);
options.ForwardWindowsAuthentication = iisConfigData.fWindowsAuthEnabled || iisConfigData.fBasicAuthEnabled;
options.MaxRequestBodySize = iisConfigData.maxRequestBodySize;
options.IisMaxRequestSizeLimit = iisConfigData.maxRequestBodySize;
}
);
});
}

return hostBuilder;
}
}