HttpMessageInvoker sample

program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApplication1 {

    class Program {

        static void Main(string[] args) {

            HttpMessageHandler handler = new Handler1() {
                InnerHandler = new Handler2() { 
                    InnerHandler = new Handler3()
                }
            };

            HttpMessageInvoker invoker = new HttpMessageInvoker(handler);
            invoker.SendAsync(new HttpRequestMessage(), CancellationToken.None);
        }
    }

    public class Handler1 : DelegatingHandler {

        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) {

            Console.WriteLine("Handler1");
            var response = await base.SendAsync(request, cancellationToken);
            Console.WriteLine("Handler1 cont.");

            return response;
        }
    }

    public class Handler2 : DelegatingHandler {

        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) {

            Console.WriteLine("Handler2");
            var response = await base.SendAsync(request, cancellationToken);
            Console.WriteLine("Handler2 cont.");

            return response;
        }
    }

    public class Handler3 : HttpMessageHandler {

        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) {

            Console.WriteLine("Handler3");
            Console.WriteLine("Handler2 cont.");

            return Task.FromResult(new HttpResponseMessage());
        }
    }
}