Added tags and channel presence

Author: Ray Tsang

appengine/channel/src/main/java/com/example/appengine/channel/ChannelPresenceServlet.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2016 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.appengine.channel;
+
+import com.google.appengine.api.channel.ChannelPresence;
+import com.google.appengine.api.channel.ChannelService;
+import com.google.appengine.api.channel.ChannelServiceFactory;
+
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+
+public class ChannelPresenceServlet extends HttpServlet {
+  @Override
+  public void doPost(HttpServletRequest req, HttpServletResponse resp)
+      throws IOException {
+    //[START channel_presence]
+    ChannelService channelService = ChannelServiceFactory.getChannelService();
+    ChannelPresence presence = channelService.parsePresence(req);
+    //[END channel_presence]
+
+    System.out.println("Client ID: " + presence.clientId() + ", Connected: " + presence.isConnected());
+    resp.setStatus(HttpServletResponse.SC_OK);
+  }
+}

appengine/channel/src/main/java/com/example/appengine/channel/Game.java

@@ -115,8 +115,9 @@ public String getMessageString() {
     return message.toString();
   }
 
+  //[START send_updates]
   public String getChannelKey(String user) {
-    return user + id;
+    return user + "." + id;
   }
 
   private void sendUpdateToUser(String user) {
@@ -131,6 +132,7 @@ public void sendUpdateToClients() {
     sendUpdateToUser(userX);
     sendUpdateToUser(userO);
   }
+  //[END send_updates]
 
   public void checkWin() {
     final Pattern[] wins;
@@ -152,6 +154,7 @@ public void checkWin() {
     }
   }
 
+  //[START make_move]
   public boolean makeMove(int position, String user) {
     String currentMovePlayer;
     char value;
@@ -175,4 +178,5 @@ public boolean makeMove(int position, String user) {
 
     return false;
   }
+  //[END make_move]
 }

appengine/channel/src/main/java/com/example/appengine/channel/TicTacToeServlet.java

@@ -82,9 +82,15 @@ public void doGet(HttpServletRequest req, HttpServletResponse resp)
       gameKey = game.getId();
     }
 
+    //[START channel_service]
     ChannelService channelService = ChannelServiceFactory.getChannelService();
+
+    // The 'Game' object exposes a method which creates a unique string based on the game's key
+    // and the user's id.
     String token = channelService.createChannel(game.getChannelKey(userId));
 
+    //[END channel_service]
+
     ofy.save().entity(game).now();
 
     req.setAttribute("game_key", gameKey);

appengine/channel/src/main/webapp/WEB-INF/appengine-web.xml

@@ -23,5 +23,11 @@
     <system-properties>
         <property name="java.util.logging.config.file" value="WEB-INF/logging.properties"/>
     </system-properties>
+    <!--[START inbound_service]-->
+    <!-- Optional: Enable Inbound Service to get notified when a client connects to or disconnects from a channel -->
+    <inbound-services>
+      <service>channel_presence</service>
+    </inbound-services>
+    <!--[END inbound_service-->
 
 </appengine-web-app>

appengine/channel/src/main/webapp/WEB-INF/view/index.jsp

@@ -154,6 +154,7 @@
         return state.userX == state.me ? 'X' : 'O';
       }
 
+      //[START send_message]
       sendMessage = function(path, opt_param) {
         path += '?gamekey=' + state.game_key;
         if (opt_param) {
@@ -163,12 +164,15 @@
         xhr.open('POST', path, true);
         xhr.send();
       };
+      //[END send_message]
 
+      //[START move_in_square]
       moveInSquare = function(id) {
         if (isMyMove() && state.board[id] == ' ') {
           sendMessage('/move', 'i=' + id);
         }
       }
+      //[END move_in_square]
 
       highlightSquare = function(id) {
         if (state.winner != "") {
@@ -205,6 +209,7 @@
       }
 
       openChannel = function() {
+        //[START open_channel]
         var token = '<%= request.getAttribute("token") %>';
         var channel = new goog.appengine.Channel(token);
         var handler = {
@@ -216,6 +221,7 @@
         var socket = channel.open(handler);
         socket.onopen = onOpened;
         socket.onmessage = onMessage;
+        //[END open_channel]
       }
 
       initialize = function() {

appengine/channel/src/main/webapp/WEB-INF/web.xml

@@ -42,6 +42,18 @@ http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
         <servlet-name>MoveServlet</servlet-name>
         <url-pattern>/move</url-pattern>
     </servlet-mapping>
+    <servlet>
+        <servlet-name>ChannelPresenceServlet</servlet-name>
+        <servlet-class>com.example.appengine.channel.ChannelPresenceServlet</servlet-class>
+    </servlet>
+    <servlet-mapping>
+        <servlet-name>ChannelPresenceServlet</servlet-name>
+        <url-pattern>/_ah/channel/connected/</url-pattern>
+    </servlet-mapping>
+    <servlet-mapping>
+        <servlet-name>ChannelPresenceServlet</servlet-name>
+        <url-pattern>/_ah/channel/disconnected/</url-pattern>
+    </servlet-mapping>
 
     <filter>
         <filter-name>ObjectifyFilter</filter-name>