Startup experience (#442)

Addresses #437 and #440

samples/DispatcherSample/Startup.cs

@@ -1,9 +1,7 @@
 // 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;
 using Microsoft.AspNetCore.Builder;
-using Microsoft.AspNetCore.Dispatcher;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Routing;
@@ -17,6 +15,7 @@ namespace DispatcherSample
         {
             services.AddSingleton<UrlGenerator>();
             services.AddSingleton<RouteValueAddressTable>();
+            services.AddDispatcher();
         }
 
         public void Configure(IApplicationBuilder app, IHostingEnvironment env)
@@ -27,47 +26,7 @@ namespace DispatcherSample
                 await next.Invoke();
             });
 
-            var dictionary = new Dictionary<string, DispatcherFeature>
+            app.UseDispatcher();
-            {
-                {
-                    "/example",
-                    new DispatcherFeature
-                        {
-                            Endpoint = new DispatcherEndpoint("example"),
-                            RequestDelegate = async (context) =>
-                            {
-                                await context.Response.WriteAsync("Hello from the example!");
-                            }
-                        }
-                },
-                {
-                    "/example2",
-                    new DispatcherFeature
-                        {
-                            Endpoint = new DispatcherEndpoint("example2"),
-                            RequestDelegate = async (context) =>
-                            {
-                                await context.Response.WriteAsync("Hello from the second example!");
-                            }
-                        }
-                },
-            };
-
-            app.Use(async (context, next) =>
-            {
-                if (dictionary.TryGetValue(context.Request.Path, out var value))
-                {
-                    var dispatcherFeature = new DispatcherFeature
-                    {
-                        Endpoint = value.Endpoint,
-                        RequestDelegate = value.RequestDelegate
-                    };
-
-                    context.Features.Set<IDispatcherFeature>(dispatcherFeature);
-                    await context.Response.WriteAsync("<p>Dispatch</p>");
-                    await next.Invoke();
-                }
-            });
 
             app.Use(async (context, next) =>
             {
@@ -76,17 +35,11 @@ namespace DispatcherSample
             });
 
             app.Use(async (context, next) =>
-            {
-                var feature = context.Features.Get<IDispatcherFeature>();
-                await feature.RequestDelegate(context);
-                await next.Invoke();
-            });
-
-            app.Run(async (context) =>
             {
                 var urlGenerator = app.ApplicationServices.GetService<UrlGenerator>();
                 var url = urlGenerator.GenerateURL(new RouteValueDictionary(new { Movie = "The Lion King", Character = "Mufasa" }), context);
                 await context.Response.WriteAsync($"<p>Generated url: {url}</p>");
+                await next.Invoke();
             });
         }
     }

src/Microsoft.AspNetCore.Dispatcher/DispatcherApplicationBuilderExtensions.cs

@@ -0,0 +1,16 @@
+// 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.AspNetCore.Dispatcher;
+
+namespace Microsoft.AspNetCore.Builder
+{
+    public static class DispatcherApplicationBuilderExtensions
+    {
+        public static IApplicationBuilder UseDispatcher(this IApplicationBuilder builder)
+        {
+            builder.Properties.Add("Dispatcher", true);
+            return builder.UseMiddleware<DispatcherMiddleware>();
+        }
+    }
+}

src/Microsoft.AspNetCore.Dispatcher/DispatcherEndpoint.cs

@@ -0,0 +1,15 @@
+// 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.AspNetCore.Dispatcher
+{
+    public class DispatcherEndpoint : Endpoint
+    {
+        public DispatcherEndpoint(string displayName)
+        {
+            DisplayName = displayName;
+        }
+
+        public override string DisplayName { get; }
+    }
+}

src/Microsoft.AspNetCore.Dispatcher/DispatcherEndpointStartupFilter.cs

@@ -0,0 +1,24 @@
+// 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;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting;
+
+namespace Microsoft.AspNetCore.Dispatcher
+{
+    public class DispatcherEndpointStartupFilter : IStartupFilter
+    {
+        public Action<IApplicationBuilder> Configure(Action<IApplicationBuilder> next)
+        {
+            return builder =>
+            {
+                next(builder);
+                if (builder.Properties.ContainsKey("Dispatcher"))
+                {
+                    builder.UseMiddleware<EndpointMiddleware>();
+                }
+            };
+        }
+    }
+}

src/Microsoft.AspNetCore.Dispatcher/DispatcherFeature.cs

@@ -1,10 +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.
 
-using Microsoft.AspNetCore.Dispatcher;
 using Microsoft.AspNetCore.Http;
 
-namespace DispatcherSample
+namespace Microsoft.AspNetCore.Dispatcher
 {
     public class DispatcherFeature : IDispatcherFeature
     {

src/Microsoft.AspNetCore.Dispatcher/DispatcherMiddleware.cs

@@ -0,0 +1,60 @@
+// 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;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Dispatcher
+{
+    public class DispatcherMiddleware
+    {
+        private readonly RequestDelegate _next;
+
+        public DispatcherMiddleware(RequestDelegate next)
+        {
+            _next = next;
+        }
+
+        public async Task Invoke(HttpContext httpContext)
+        {
+            var dictionary = new Dictionary<string, DispatcherFeature>
+            {
+                {
+                    "/example",
+                    new DispatcherFeature
+                        {
+                            Endpoint = new DispatcherEndpoint("example"),
+                            RequestDelegate = async (context) =>
+                            {
+                                await context.Response.WriteAsync("Hello from the example!");
+                            }
+                        }
+                },
+                {
+                    "/example2",
+                    new DispatcherFeature
+                        {
+                            Endpoint = new DispatcherEndpoint("example2"),
+                            RequestDelegate = async (context) =>
+                            {
+                                await context.Response.WriteAsync("Hello from the second example!");
+                            }
+                        }
+                },
+            };
+
+            if (dictionary.TryGetValue(httpContext.Request.Path, out var value))
+            {
+                var dispatcherFeature = new DispatcherFeature
+                {
+                    Endpoint = value.Endpoint,
+                    RequestDelegate = value.RequestDelegate
+                };
+
+                httpContext.Features.Set<IDispatcherFeature>(dispatcherFeature);
+                await _next(httpContext);
+            }
+        }
+    }
+}

src/Microsoft.AspNetCore.Dispatcher/DispatcherServiceCollectionExtensions.cs

@@ -0,0 +1,23 @@
+// 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;
+using Microsoft.AspNetCore.Dispatcher;
+using Microsoft.AspNetCore.Hosting;
+
+namespace Microsoft.Extensions.DependencyInjection
+{
+    public static class DispatcherServiceCollectionExtensions
+    {
+        public static IServiceCollection AddDispatcher(this IServiceCollection services)
+        {
+            if (services == null)
+            {
+                throw new ArgumentNullException(nameof(services));
+            }
+
+            services.AddSingleton<IStartupFilter, DispatcherEndpointStartupFilter>();
+            return services;
+        }
+    }
+}

src/Microsoft.AspNetCore.Dispatcher/EndpointMiddleware.cs

@@ -0,0 +1,31 @@
+// 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.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Dispatcher
+{
+    public class EndpointMiddleware
+    {
+        private RequestDelegate _next;
+
+        public EndpointMiddleware(RequestDelegate next)
+        {
+            _next = next;
+        }
+
+        public async Task Invoke(HttpContext context)
+        {
+            var feature = context.Features.Get<IDispatcherFeature>();
+            if (feature.RequestDelegate == null)
+            {
+                await _next(context);
+            }
+            else
+            {
+                await feature.RequestDelegate(context);
+            }
+        }
+    }
+}

src/Microsoft.AspNetCore.Dispatcher/Microsoft.AspNetCore.Dispatcher.csproj

@@ -12,6 +12,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.AspNetCore.Hosting" />
     <PackageReference Include="Microsoft.AspNetCore.Http.Extensions" />
   </ItemGroup>