1 /**
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements.  See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership.  The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License.  You may obtain a copy of the License at
9 *
10 *     http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18 
19 package org.apache.hadoop.yarn.webapp.example;
20 
21 import org.apache.hadoop.classification.InterfaceAudience;
22 import org.apache.hadoop.yarn.webapp.Controller;
23 import org.apache.hadoop.yarn.webapp.WebApps;
24 import org.apache.hadoop.yarn.webapp.view.HtmlPage;
25 
26 /**
27  * The obligatory example. No xml/jsp/templates/config files! No
28  * proliferation of strange annotations either :)
29  *
30  * <p>3 in 1 example. Check results at
31  * <br>http://localhost:8888/hello and
32  * <br>http://localhost:8888/hello/html
33  * <br>http://localhost:8888/hello/json
34  */
35 @InterfaceAudience.LimitedPrivate({"YARN", "MapReduce"})
36 public class HelloWorld {
37   public static class Hello extends Controller {
index()38     @Override public void index() { renderText("Hello world!"); }
html()39     public void html() { setTitle("Hello world!"); }
json()40     public void json() { renderJSON("Hello world!"); }
41   }
42 
43   public static class HelloView extends HtmlPage {
render(Page.HTML<_> html)44     @Override protected void render(Page.HTML<_> html) {
45       html. // produces valid html 4.01 strict
46         title($("title")).
47         p("#hello-for-css").
48           _($("title"))._()._();
49     }
50   }
51 
main(String[] args)52   public static void main(String[] args) {
53     WebApps.$for(new HelloWorld()).at(8888).inDevMode().start().joinThread();
54   }
55 }
56