Added some wrapper around the http context so i can at least pretend to access things from it without casting them

src/Ocelot.Library/Infrastructure/Services/CannotAddDataError.cs

@@ -0,0 +1,11 @@
+using Ocelot.Library.Infrastructure.Responses;
+
+namespace Ocelot.Library.Infrastructure.Services
+{
+    public class CannotAddDataError : Error
+    {
+        public CannotAddDataError(string message) : base(message)
+        {
+        }
+    }
+}

src/Ocelot.Library/Infrastructure/Services/CannotFindDataError.cs

@@ -0,0 +1,11 @@
+using Ocelot.Library.Infrastructure.Responses;
+
+namespace Ocelot.Library.Infrastructure.Services
+{
+    public class CannotFindDataError : Error
+    {
+        public CannotFindDataError(string message) : base(message)
+        {
+        }
+    }
+}

src/Ocelot.Library/Infrastructure/Services/IRequestDataService.cs

@@ -0,0 +1,10 @@
+using Ocelot.Library.Infrastructure.Responses;
+
+namespace Ocelot.Library.Infrastructure.Services
+{
+    public interface IRequestDataService
+    {
+        Response Add<T>(string key, T value);
+        Response<T> Get<T>(string key);
+    }
+}

src/Ocelot.Library/Infrastructure/Services/RequestDataService.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Collections.Generic;
+using Microsoft.AspNetCore.Http;
+using Ocelot.Library.Infrastructure.Responses;
+
+namespace Ocelot.Library.Infrastructure.Services
+{
+    public class RequestDataService : IRequestDataService
+    {
+        private readonly IHttpContextAccessor _httpContextAccessor;
+
+        public RequestDataService(IHttpContextAccessor httpContextAccessor)
+        {
+            _httpContextAccessor = httpContextAccessor;
+        }
+
+        public Response Add<T>(string key, T value)
+        {
+            try
+            {
+                _httpContextAccessor.HttpContext.Items.Add(key, value);
+                return new OkResponse();
+            }
+            catch (Exception exception)
+            {
+                return new ErrorResponse(new List<Error>
+                {
+                    new CannotAddDataError(string.Format($"Unable to add data for key: {key}, exception: {exception.Message}"))
+                });
+            }
+        }
+
+        public Response<T> Get<T>(string key)
+        {
+            object obj;
+
+            if(_httpContextAccessor.HttpContext.Items.TryGetValue(key, out obj))
+            {
+                var data = (T) obj;
+                return new OkResponse<T>(data);
+            }
+
+            return new ErrorResponse<T>(new List<Error>
+            {
+                new CannotFindDataError($"Unable to find data for key: {key}")
+            });
+        } 
+    }
+}

src/Ocelot.Library/Middleware/DownstreamRouteFinderMiddleware.cs

@@ -2,6 +2,7 @@ using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Ocelot.Library.Infrastructure.DownstreamRouteFinder;
 using Ocelot.Library.Infrastructure.Responder;
+using Ocelot.Library.Infrastructure.Services;
 
 namespace Ocelot.Library.Middleware
 {
@@ -10,14 +11,17 @@ namespace Ocelot.Library.Middleware
         private readonly RequestDelegate _next;
         private readonly IDownstreamRouteFinder _downstreamRouteFinder;
         private readonly IHttpResponder _responder;
+        private readonly IRequestDataService _requestDataService;
 
         public DownstreamRouteFinderMiddleware(RequestDelegate next, 
             IDownstreamRouteFinder downstreamRouteFinder, 
-            IHttpResponder responder)
+            IHttpResponder responder,
+            IRequestDataService requestDataService)
         {
             _next = next;
             _downstreamRouteFinder = downstreamRouteFinder;
             _responder = responder;
+            _requestDataService = requestDataService;
         }
 
         public async Task Invoke(HttpContext context)
@@ -32,7 +36,7 @@ namespace Ocelot.Library.Middleware
                 return;
             }
 
-            context.Items.Add("DownstreamRoute", downstreamRoute.Data);
+            _requestDataService.Add("DownstreamRoute", downstreamRoute.Data);
             
             await _next.Invoke(context);
         }

src/Ocelot.Library/Middleware/DownstreamUrlCreatorMiddleware.cs

@@ -1,6 +1,8 @@
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Ocelot.Library.Infrastructure.DownstreamRouteFinder;
+using Ocelot.Library.Infrastructure.Responder;
+using Ocelot.Library.Infrastructure.Services;
 using Ocelot.Library.Infrastructure.UrlTemplateReplacer;
 
 namespace Ocelot.Library.Middleware
@@ -9,34 +11,35 @@ namespace Ocelot.Library.Middleware
     {
         private readonly RequestDelegate _next;
         private readonly IDownstreamUrlTemplateVariableReplacer _urlReplacer;
+        private readonly IRequestDataService _requestDataService;
+        private readonly IHttpResponder _responder;
 
         public DownstreamUrlCreatorMiddleware(RequestDelegate next, 
-            IDownstreamUrlTemplateVariableReplacer urlReplacer)
+            IDownstreamUrlTemplateVariableReplacer urlReplacer,
+            IRequestDataService requestDataService, 
+            IHttpResponder responder)
         {
             _next = next;
             _urlReplacer = urlReplacer;
+            _requestDataService = requestDataService;
+            _responder = responder;
         }
 
         public async Task Invoke(HttpContext context)
         {
-            var downstreamRoute = GetDownstreamRouteFromOwinItems(context);
+            var downstreamRoute = _requestDataService.Get<DownstreamRoute>("DownstreamRoute");
 
-            var downstreamUrl = _urlReplacer.ReplaceTemplateVariables(downstreamRoute);
-
-            context.Items.Add("DownstreamUrl", downstreamUrl);
-
-            await _next.Invoke(context);
-        }
-
-        private DownstreamRoute GetDownstreamRouteFromOwinItems(HttpContext context)
-        {
-            object obj;
-            DownstreamRoute downstreamRoute = null;
-            if (context.Items.TryGetValue("DownstreamRoute", out obj))
+            if (downstreamRoute.IsError)
             {
-                downstreamRoute = (DownstreamRoute) obj;
+                await _responder.CreateNotFoundResponse(context);
+                return;
             }
-            return downstreamRoute;
+
+            var downstreamUrl = _urlReplacer.ReplaceTemplateVariables(downstreamRoute.Data);
+
+            _requestDataService.Add("DownstreamUrl", downstreamUrl);
+                
+            await _next.Invoke(context);
         }
     }
 }

src/Ocelot.Library/Middleware/HttpRequesterMiddleware.cs

@@ -2,6 +2,7 @@ using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Ocelot.Library.Infrastructure.Requester;
 using Ocelot.Library.Infrastructure.Responder;
+using Ocelot.Library.Infrastructure.Services;
 
 namespace Ocelot.Library.Middleware
 {
@@ -10,38 +11,36 @@ namespace Ocelot.Library.Middleware
         private readonly RequestDelegate _next;
         private readonly IHttpRequester _requester;
         private readonly IHttpResponder _responder;
+        private readonly IRequestDataService _requestDataService;
 
         public HttpRequesterMiddleware(RequestDelegate next, 
             IHttpRequester requester, 
-            IHttpResponder responder)
+            IHttpResponder responder,
+            IRequestDataService requestDataService)
         {
             _next = next;
             _requester = requester;
             _responder = responder;
+            _requestDataService = requestDataService;
         }
 
         public async Task Invoke(HttpContext context)
         {
-            var downstreamUrl = GetDownstreamUrlFromOwinItems(context);
+            var downstreamUrl = _requestDataService.Get<string>("DownstreamUrl");
+
+            if (downstreamUrl.IsError)
+            {
+                await _responder.CreateNotFoundResponse(context);
+                return;
+            }
 
             var response = await _requester
-                .GetResponse(context.Request.Method, downstreamUrl, context.Request.Body, 
+                .GetResponse(context.Request.Method, downstreamUrl.Data, context.Request.Body, 
                 context.Request.Headers, context.Request.Cookies, context.Request.Query, context.Request.ContentType);
 
             await _responder.CreateResponse(context, response);
 
             await _next.Invoke(context);
         }
-
-        private string GetDownstreamUrlFromOwinItems(HttpContext context)
-        {
-            object obj;
-            string downstreamUrl = null;
-            if (context.Items.TryGetValue("DownstreamUrl", out obj))
-            {
-                downstreamUrl = (string) obj;
-            }
-            return downstreamUrl;
-        }
     }
 }

src/Ocelot/Startup.cs

@@ -1,11 +1,13 @@
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Ocelot.Library.Infrastructure.DownstreamRouteFinder;
 using Ocelot.Library.Infrastructure.Requester;
 using Ocelot.Library.Infrastructure.Responder;
+using Ocelot.Library.Infrastructure.Services;
 using Ocelot.Library.Middleware;
 
 namespace Ocelot
@@ -42,6 +44,10 @@ namespace Ocelot
             services.AddSingleton<IDownstreamRouteFinder, DownstreamRouteFinder>();
             services.AddSingleton<IHttpRequester, HttpClientHttpRequester>();
             services.AddSingleton<IHttpResponder, HttpContextResponder>();
+
+            // see this for why we register this as singleton http://stackoverflow.com/questions/37371264/invalidoperationexception-unable-to-resolve-service-for-type-microsoft-aspnetc
+            services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
+            services.AddScoped<IRequestDataService, RequestDataService>();
         }
 
         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.

test/Ocelot.UnitTests/Services/RequestDataServiceTests.cs

@@ -0,0 +1,83 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using Moq;
+using Ocelot.Library.Infrastructure.Responses;
+using Ocelot.Library.Infrastructure.Services;
+using Shouldly;
+using TestStack.BDDfy;
+using Xunit;
+
+namespace Ocelot.UnitTests.Services
+{
+    public class RequestDataServiceTests
+    {
+        private IRequestDataService _requestDataService;
+        private IHttpContextAccessor _httpContextAccesor;
+        private string _key;
+        private object _toAdd;
+        private Response<int[]> _result;
+
+        public RequestDataServiceTests()
+        {
+            _httpContextAccesor = new HttpContextAccessor();
+            _httpContextAccesor.HttpContext = new DefaultHttpContext();
+            _requestDataService = new RequestDataService(_httpContextAccesor);
+        }
+
+        [Fact]
+        public void should_add_item()
+        {
+            this.Given(x => x.GivenIHaveAnItemToAdd("blahh", new [] {1,2,3,4}))
+                .When(x => x.WhenIAddTheItem())
+                .Then(x => x.ThenTheItemIsAdded())
+                .BDDfy();
+        }
+
+        [Fact]
+        public void should_get_item()
+        {
+            this.Given(x => x.GivenThereIsAnItemInTheContext("chest"))
+                .When(x => x.WhenIGetTheItem())
+                .Then(x => x.ThenTheItemIsReturned())
+                .BDDfy();
+        }
+
+        private void ThenTheItemIsReturned()
+        {
+            _result.IsError.ShouldBeFalse();
+            _result.Data.ShouldNotBeNull();
+        }
+
+        private void WhenIGetTheItem()
+        {
+            _result = _requestDataService.Get<int[]>(_key);
+        }
+
+        private void GivenThereIsAnItemInTheContext(string key)
+        {
+            _key = key;
+            var data = new[] {5435345};
+            _httpContextAccesor.HttpContext.Items.Add(key, data);
+        }
+
+        private void GivenIHaveAnItemToAdd(string key, object toAdd)
+        {
+            _key = key;
+            _toAdd = toAdd;
+        }
+
+        private void WhenIAddTheItem()
+        {
+            _requestDataService.Add(_key, _toAdd);
+        }
+
+        private void ThenTheItemIsAdded()
+        {
+            object obj;
+            _httpContextAccesor.HttpContext.Items.TryGetValue(_key, out obj).ShouldBeTrue();
+        }
+    }
+}