J'ai suivi le tutoriel . Après avoir changé app/maint.tsdans le chapitre Http, j'obtiens l'erreur lors du démarrage de l'application via la ligne de commande:
app / main.ts (5,51): erreur TS2307: Impossible de trouver le module 'angular2-in-memory-web-api'.
(Visual Studio Code me donne la même erreur dans main.ts - soulignement ondulé rouge.)
Voici mon systemjs.config.js:
/**
 * System configuration for Angular 2 samples
 * Adjust as necessary for your application needs.
 */
(function(global) {
  // map tells the System loader where to look for things
  var map = {
    'app':                        'app', // 'dist',
    '@angular':                   'node_modules/@angular',
    'angular2-in-memory-web-api': 'node_modules/angular2-in-memory-web-api',
    'rxjs':                       'node_modules/rxjs'
  };
  // packages tells the System loader how to load when no filename and/or no extension
  var packages = {
    'app':                        { main: 'main.js',  defaultExtension: 'js' },
    'rxjs':                       { defaultExtension: 'js' },
    'angular2-in-memory-web-api': { defaultExtension: 'js' },
  };
  var ngPackageNames = [
    'common',
    'compiler',
    'core',
    'http',
    'platform-browser',
    'platform-browser-dynamic',
    'router',
    'router-deprecated',
    'upgrade',
  ];
  // Add package entries for angular packages
  ngPackageNames.forEach(function(pkgName) {
    packages['@angular/'+pkgName] = { main: pkgName + '.umd.js', defaultExtension: 'js' };
  });
  var config = {
    map: map,
    packages: packages
  }
  System.config(config);
})(this);
Voici mon app/main.ts:
// Imports for loading & configuring the in-memory web api
import { provide }    from '@angular/core';
import { XHRBackend } from '@angular/http';
import { InMemoryBackendService, SEED_DATA } from 'angular2-in-memory-web-api';
import { InMemoryDataService }               from './in-memory-data.service';
// The usual bootstrapping imports
import { bootstrap }      from '@angular/platform-browser-dynamic';
import { HTTP_PROVIDERS } from '@angular/http';
import { AppComponent }   from './app.component';
bootstrap(AppComponent, [
    HTTP_PROVIDERS,
    provide(XHRBackend, { useClass: InMemoryBackendService }), // in-mem server
    provide(SEED_DATA,  { useClass: InMemoryDataService })     // in-mem server data
]);
          
'angular2-in-memory-web-api': { main: 'index.js', defaultExtension: 'js' }dans le fichier systemjs.config.js (voir la réponse de @GrantTaylor).