Implement cache priming prototype

Microsoft.AspNet.AngularServices/PrimeCacheHelper.cs

@@ -0,0 +1,44 @@
+using System;
+using System.Net;
+using System.Net.Http;
+using System.Threading.Tasks;
+using Microsoft.AspNet.Mvc.Rendering;
+using Microsoft.Extensions.Logging;
+using Newtonsoft.Json;
+
+namespace Microsoft.AspNet.AngularServices {
+    public static class PrimeCacheHelper {
+        public static async Task<HtmlString> PrimeCache(this IHtmlHelper html, string url) {
+            // TODO: Consider deduplicating the PrimeCache calls (that is, if there are multiple requests to precache
+            // the same URL, only return nonempty for one of them). This will make it easier to auto-prime-cache any
+            // HTTP requests made during server-side rendering, without risking unnecessary duplicate requests.
+            
+            if (string.IsNullOrEmpty(url)) {
+                throw new ArgumentException("Value cannot be null or empty", "url");
+            }
+
+            try {
+                var request = html.ViewContext.HttpContext.Request;
+                var baseUri = new Uri(string.Concat(request.Scheme, "://", request.Host.ToUriComponent(), request.PathBase.ToUriComponent(), request.Path.ToUriComponent(), request.QueryString.ToUriComponent()));
+                var fullUri = new Uri(baseUri, url);
+                var response = await new HttpClient().GetAsync(fullUri.ToString());
+                var responseBody = await response.Content.ReadAsStringAsync();
+                return new HtmlString(FormatAsScript(url, response.StatusCode, responseBody));
+            } catch (Exception ex) {
+                var logger = (ILogger)html.ViewContext.HttpContext.ApplicationServices.GetService(typeof (ILogger));
+                if (logger != null) {
+                    logger.LogWarning("Error priming cache for URL: " + url, ex);
+                }
+                return new HtmlString(string.Empty);
+            }
+        }
+
+        private static string FormatAsScript(string url, HttpStatusCode responseStatusCode, string responseBody)
+        {
+            return string.Format(@"<script>window.__preCachedResponses = window.__preCachedResponses || {{}}; window.__preCachedResponses[{0}] = {1};</script>",
+                JsonConvert.SerializeObject(url),
+                JsonConvert.SerializeObject(new { statusCode = responseStatusCode, body = responseBody })
+            );
+        }
+    }
+}

Microsoft.AspNet.AngularServices/npm/build.js

@@ -12,7 +12,8 @@ builder.config({
         'angular2-aspnet/*': 'dist/*'
     },
     meta: {
-        'angular2/*': { build: false }
+        'angular2/*': { build: false },
+        '@reactivex/*': { build: false }
     }
 });
 

Microsoft.AspNet.AngularServices/npm/package.json

@@ -1,6 +1,6 @@
 {
   "name": "angular2-aspnet",
-  "version": "0.0.1",
+  "version": "0.0.3",
   "description": "Helpers for Angular 2 apps built on ASP.NET",
   "main": "./dist/Exports",
   "scripts": {
@@ -15,7 +15,7 @@
   "author": "Microsoft",
   "license": "Apache-2.0",
   "peerDependencies": {
-    "angular2": "^2.0.0-alpha.44"
+    "angular2": "2.0.0-alpha.44"
   },
   "devDependencies": {
     "systemjs-builder": "^0.14.11",

Microsoft.AspNet.AngularServices/npm/src/CachePrimedHttp.ts

@@ -0,0 +1,63 @@
+import { provide, Injectable, Provider } from 'angular2/core';
+import { Connection, ConnectionBackend, Http, XHRBackend, RequestOptions, Request, RequestMethods, Response, ResponseOptions, ReadyStates } from 'angular2/http';
+
+@Injectable()
+export class CachePrimedConnectionBackend extends ConnectionBackend {
+    private _preCachedResponses: PreCachedResponses;
+    
+    constructor(private _underlyingBackend: ConnectionBackend, private _baseResponseOptions: ResponseOptions) {
+        super();
+        this._preCachedResponses = (<any>window).__preCachedResponses || {};
+    }
+    
+    public createConnection(request: Request): Connection {
+        let cacheKey = request.url;
+        if (request.method === RequestMethods.Get && this._preCachedResponses.hasOwnProperty(cacheKey)) {
+            return new CacheHitConnection(request, this._preCachedResponses[cacheKey], this._baseResponseOptions);
+        } else {
+            return this._underlyingBackend.createConnection(request);
+        }
+    }
+}
+
+class CacheHitConnection implements Connection {
+    readyState: ReadyStates;
+    request: Request;
+    response: any;
+
+    constructor (req: Request, cachedResponse: PreCachedResponse, baseResponseOptions: ResponseOptions) {
+        this.request = req;
+        this.readyState = ReadyStates.Done;
+        
+        // Workaround for difficulty consuming CommonJS default exports in TypeScript. Note that it has to be a dynamic
+        // 'require', and not an 'import' statement, because the module isn't available on the server.
+        // All this badness goes away with the next update of Angular 2, as it exposes Observable directly from angular2/core.
+        // --
+        // The current version of Angular exposes the following SystemJS module directly (it is *not* coming from the
+        // @reactivex/rxjs NPM package - it's coming from angular2).
+        let obsCtor: any = require('@reactivex/rxjs/dist/cjs/Observable');
+        this.response = new obsCtor(responseObserver => {
+            let response = new Response(new ResponseOptions({ body: cachedResponse.body, status: cachedResponse.statusCode }));
+            responseObserver.next(response);
+            responseObserver.complete();
+        });
+    }
+}
+
+declare var require: any; // Part of the workaround mentioned below. Can remove this after updating Angular.
+
+interface PreCachedResponses {
+    [url: string]: PreCachedResponse;
+}
+
+interface PreCachedResponse {
+    statusCode: number;
+    body: string;
+}
+
+export const CACHE_PRIMED_HTTP_PROVIDERS = [
+    provide(Http, {
+        useFactory: (xhrBackend, requestOptions, responseOptions) => new Http(new CachePrimedConnectionBackend(xhrBackend, responseOptions), requestOptions),
+        deps: [XHRBackend, RequestOptions, ResponseOptions]
+    }),
+];

Microsoft.AspNet.AngularServices/npm/src/Exports.ts

@@ -1 +1,2 @@
+export * from './CachePrimedHttp';
 export * from './Validation';

Microsoft.AspNet.AngularServices/npm/tsconfig.json

@@ -4,6 +4,7 @@
     "target": "es5",
     "sourceMap": false,
     "declaration": true,
+    "experimentalDecorators": true,
     "noLib": false,
     "outDir": "./dist"
   },

Microsoft.AspNet.AngularServices/project.json

@@ -19,6 +19,7 @@
         "Microsoft.CSharp": "4.0.1-beta-*",
         "System.Collections": "4.0.11-beta-*",
         "System.Linq": "4.0.1-beta-*",
+        "System.Net.Http": "4.0.1-beta-*",
         "System.Runtime": "4.0.21-beta-*",
         "System.Threading": "4.0.11-beta-*"
       }