Event Notification for MVC Prototype

Here's a first take on the pattern for publishing notifications from MVC.

src/Microsoft.AspNet.Mvc.Core/MvcRouteHandler.cs

@@ -2,7 +2,6 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using System.Linq;
 using System.Diagnostics;
 using System.Threading.Tasks;
 using Microsoft.AspNet.Http;
@@ -12,12 +11,13 @@ using Microsoft.AspNet.Routing;
 using Microsoft.Framework.DependencyInjection;
 using Microsoft.Framework.Internal;
 using Microsoft.Framework.Logging;
-using Microsoft.Framework.OptionsModel;
+using Microsoft.Framework.Notification;
 
 namespace Microsoft.AspNet.Mvc
 {
     public class MvcRouteHandler : IRouter
     {
+        private INotifier _notifier;
         private ILogger _logger;
 
         public VirtualPathData GetVirtualPath([NotNull] VirtualPathContext context)
@@ -40,6 +40,8 @@ namespace Microsoft.AspNet.Mvc
             MvcServicesHelper.ThrowIfMvcNotRegistered(services);
 
             EnsureLogger(context.HttpContext);
+            EnsureNotifier(context.HttpContext);
+
             var actionSelector = services.GetRequiredService<IActionSelector>();
             var actionDescriptor = await actionSelector.SelectAsync(context);
 
@@ -69,6 +71,13 @@ namespace Microsoft.AspNet.Mvc
             {
                 context.RouteData = newRouteData;
 
+                if (_notifier.ShouldNotify("Microsoft.AspNet.Mvc.ActionSelected"))
+                {
+                    _notifier.Notify(
+                        "Microsoft.AspNet.Mvc.ActionSelected",
+                        new { actionDescriptor, httpContext = context.HttpContext, routeData = context.RouteData});
+                }
+
                 using (_logger.BeginScope("ActionId: {ActionId}", actionDescriptor.Id))
                 {
                     _logger.LogVerbose("Executing action {ActionDisplayName}", actionDescriptor.DisplayName);
@@ -115,5 +124,13 @@ namespace Microsoft.AspNet.Mvc
                 _logger = factory.CreateLogger<MvcRouteHandler>();
             }
         }
+
+        private void EnsureNotifier(HttpContext context)
+        {
+            if (_notifier == null)
+            {
+                _notifier = context.RequestServices.GetRequiredService<INotifier>();
+            }
+        }
     }
 }

src/Microsoft.AspNet.Mvc.Core/project.json

@@ -21,6 +21,7 @@
         "Microsoft.Framework.ClosedGenericMatcher.Sources": { "version": "1.0.0-*", "type": "build" },
         "Microsoft.Framework.CopyOnWriteDictionary.Sources": { "version": "1.0.0-*", "type": "build" },
         "Microsoft.Framework.Logging.Abstractions": "1.0.0-*",
+        "Microsoft.Framework.Notification": "1.0.0-*",
         "Microsoft.Framework.NotNullAttribute.Sources": { "version": "1.0.0-*", "type": "build" },
         "Microsoft.Framework.PropertyActivator.Sources": { "version": "1.0.0-*", "type": "build" },
         "Microsoft.Framework.PropertyHelper.Sources": { "version": "1.0.0-*", "type": "build" },

src/Microsoft.AspNet.Mvc/MvcServiceCollectionExtensions.cs

@@ -299,6 +299,7 @@ namespace Microsoft.Framework.DependencyInjection
             services.AddCors();
             services.AddAuthorization();
             services.AddWebEncoders();
+            services.AddNotifier();
             services.Configure<RouteOptions>(
                 routeOptions => routeOptions.ConstraintMap.Add("exists", typeof(KnownRouteValueConstraint)));
         }

test/Microsoft.AspNet.Mvc.Core.Test/MvcRouteHandlerTests.cs

@@ -5,9 +5,11 @@ using System;
 using System.Threading.Tasks;
 using Microsoft.AspNet.Http;
 using Microsoft.AspNet.Mvc.Internal;
+using Microsoft.AspNet.Mvc.TestCommon.Notification;
 using Microsoft.AspNet.Routing;
 using Microsoft.Framework.Logging;
 using Microsoft.Framework.Logging.Testing;
+using Microsoft.Framework.Notification;
 using Microsoft.Framework.OptionsModel;
 using Moq;
 using Xunit;
@@ -152,12 +154,38 @@ namespace Microsoft.AspNet.Mvc
             Assert.Equal(initialRouter, Assert.Single(actionRouteData.Routers));
         }
 
+        [Fact]
+        public async Task RouteAsync_Notifies_ActionSelected()
+        {
+            // Arrange
+            var listener = new TestNotificationListener();
+
+            var context = CreateRouteContext(notificationListener: listener);
+            context.RouteData.Values.Add("tag", "value");
+
+            var handler = new MvcRouteHandler();
+
+            // Act
+            await handler.RouteAsync(context);
+
+            // Assert
+            Assert.NotNull(listener?.ActionSelected.ActionDescriptor);
+            Assert.NotNull(listener?.ActionSelected.HttpContext);
+
+            var routeValues = listener?.ActionSelected?.RouteData?.Values;
+            Assert.NotNull(routeValues);
+
+            Assert.Equal(1, routeValues.Count);
+            Assert.Contains(routeValues, kvp => kvp.Key == "tag" && string.Equals(kvp.Value, "value"));
+        }
+
         private RouteContext CreateRouteContext(
             ActionDescriptor actionDescriptor = null,
             IActionSelector actionSelector = null,
             IActionInvokerFactory invokerFactory = null,
             ILoggerFactory loggerFactory = null,
-            IOptions<MvcOptions> optionsAccessor = null)
+            IOptions<MvcOptions> optionsAccessor = null,
+            object notificationListener = null)
         {
             var mockContextAccessor = new Mock<IScopedInstance<ActionContext>>();
 
@@ -203,6 +231,12 @@ namespace Microsoft.AspNet.Mvc
                 optionsAccessor = options.Object;
             }
 
+            var notifier = new Notifier(new NotifierMethodAdapter());
+            if (notificationListener != null)
+            {
+                notifier.EnlistTarget(notificationListener);
+            }
+
             var httpContext = new Mock<HttpContext>();
             httpContext.Setup(h => h.RequestServices.GetService(typeof(IScopedInstance<ActionContext>)))
                 .Returns(mockContextAccessor.Object);
@@ -216,6 +250,8 @@ namespace Microsoft.AspNet.Mvc
                  .Returns(new MvcMarkerService());
             httpContext.Setup(h => h.RequestServices.GetService(typeof(IOptions<MvcOptions>)))
                  .Returns(optionsAccessor);
+            httpContext.Setup(h => h.RequestServices.GetService(typeof(INotifier)))
+                .Returns(notifier);
 
             return new RouteContext(httpContext.Object);
         }

test/Microsoft.AspNet.Mvc.TestCommon/Notification/IActionDescriptor.cs

@@ -0,0 +1,9 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNet.Mvc.TestCommon.Notification
+{
+    public interface IActionDescriptor
+    {
+    }
+}

test/Microsoft.AspNet.Mvc.TestCommon/Notification/IHttpContext.cs

@@ -0,0 +1,9 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNet.Mvc.TestCommon.Notification
+{
+    public interface IHttpContext
+    {
+    }
+}

test/Microsoft.AspNet.Mvc.TestCommon/Notification/IRouteData.cs

@@ -0,0 +1,14 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+
+namespace Microsoft.AspNet.Mvc.TestCommon.Notification
+{
+    public interface IRouteData
+    {
+        IReadOnlyList<object> Routers { get; }
+        IDictionary<string, object> DataTokens { get; }
+        IDictionary<string, object> Values { get; }
+    }
+}

test/Microsoft.AspNet.Mvc.TestCommon/Notification/TestNotificationListener.cs

@@ -0,0 +1,33 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.Framework.Notification;
+
+namespace Microsoft.AspNet.Mvc.TestCommon.Notification
+{
+    public class TestNotificationListener
+    {
+        public OnActionSelectedEventData ActionSelected { get; set; }
+
+        [NotificationName("Microsoft.AspNet.Mvc.ActionSelected")]
+        public virtual void OnActionSelected(
+            IHttpContext httpContext,
+            IRouteData routeData,
+            IActionDescriptor actionDescriptor)
+        {
+            ActionSelected = new OnActionSelectedEventData()
+            {
+                ActionDescriptor = actionDescriptor,
+                HttpContext = httpContext,
+                RouteData = routeData,
+            };
+        }
+
+        public class OnActionSelectedEventData
+        {
+            public IActionDescriptor ActionDescriptor { get; set; }
+            public IHttpContext HttpContext { get; set; }
+            public IRouteData RouteData { get; set; }
+        }
+    }
+}

test/Microsoft.AspNet.Mvc.TestCommon/project.json

@@ -1,6 +1,6 @@
 {
     "version": "6.0.0-*",
-    "shared": "*.cs",
+    "shared": "**/*.cs",
     "dependencies": {
     }
 }