Routing and dispatching

The routing and dispatching stage primarily involves the execution of a series of message handlers, which process the incoming request and then delegate them to the next message handler for processing. In earlier versions of ASP.NET Web API, we could only configure message handlers globally per application. All the message handlers were added to the HttpConfiguration.MessageHandlers collection and were executed for each request. The global configuration was enabled using the Register method in the WebApiConfig.cs file, which gets added when creating a new ASP.NET Web API project. We talk more about the WebApiConfig and Register method in the Creating our first ASP.NET Web API section. The following snippet show a sample Register method definition:

public static void Register(HttpConfiguration config)
{

    config.Routes.MapHttpRoute(
       name: "DefaultApi",
       routeTemplate: "api/{controller}/{id}",
       defaults: new { id = RouteParameter...