HTTP/2 and ASP.NET Core MVC - Protocol based content delivery

Two weeks ago I've given a talk at DevConf conference about HTTP/2. During that talk I've mentioned protocol based content delivery as potential way to optimize an application for HTTP/2 users, without degradation in performance for HTTP/1 users at the same time. After the talk I was asked for some code examples. I've decided that it's a great opportunity to spin up ASP.NET Core 2.2 preview (which brings HTTP/2 to ASP.NET Core) and play with it.

The idea behind protocol based content delivery is to branch application logic (usually rendering) based on protocol of current request (in ASP.NET Core this information is available through HttpRequest.Protocol property) in order to employ different optimization strategy. In ASP.NET Core MVC there are multiple levels on which we can branch, depending on how precise we want to be and how far we want to separate logic for different protocols. I'll go through those levels, starting from the bottom.

Conditional rendering

The simplest thing that can be done, is putting an if into a view. This will allow for rendering different blocks of HTML for different protocols. In order to avoid reaching to HttpRequest.Protocol property directly from view, protocol check can be exposed through HtmlHelper.

public static class HtmlHelperHttp2Extensions
{
    public static bool IsHttp2(this IHtmlHelper htmlHelper)
    {
        if (htmlHelper == null)
        {
            throw new ArgumentNullException(nameof(htmlHelper));
        }

        return (htmlHelper.ViewContext.HttpContext.Request.Protocol == "HTTP/2");
    }
}

This provides an easy solution for having different bundling strategies for HTTP/2 (in order to make better use of multiplexing).

@if (