<module>pusher-chat</module>

This sample demonstrates how to use the [Pusher][pusher] on [Google App Engine][ae-docs].

Pusher enables you to create public / private channels with presence information for real time messaging.

This application demonstrates presence channels in Pusher using chat rooms.

All users joining the chat room are authenticated using the `/authorize` endpoint.

All users currently in the chat room receive updates of users joining / leaving the room.

[Java HTTP library](https://github.com/pusher/pusher-http-java) is used for publishing messages to the channel

and the [JS Websocket library](https://github.com/pusher/pusher-js) is used for subscribing.

[pusher]: https://pusher.com

[ae-docs]: https://cloud.google.com/appengine/docs/java/

Install the [Google Cloud SDK](https://cloud.google.com/sdk/) and run:

If this is your first time creating an App engine application:

- Create a [Pusher] application and note down the `app_id`, `app_key`, `app_secret` and the cluster.

- Update [appengine-web.xml](src/main/webapp/WEB-INF/appengine-web.xml) with these credentials.

Access [http://localhost:8080](http://localhost:8080) via the browser, login and join the chat room.

The chat window will contain a link you can use to join the room as a different user in another browser.

You should now be able to view both the users within the chat application window and send messages to one another.

- Deploy the application to the project

```

```

Access `https://YOUR_PROJECT_ID.appspot.com`

<project>

<modelVersion>4.0.0</modelVersion>

<packaging>war</packaging>

<version>1.0-SNAPSHOT</version>

<groupId>com.example.appengine</groupId>

<artifactId>appengine-pusher-chat</artifactId>

<parent>

<groupId>com.google.cloud</groupId>

<artifactId>appengine-doc-samples</artifactId>

<version>1.0.0</version>

<relativePath>..</relativePath>

</parent>

<properties>

<maven.compiler.source>1.7</maven.compiler.source>

<maven.compiler.target>1.7</maven.compiler.target>

</properties>

<dependencies>

<dependency>

<groupId>com.pusher</groupId>

<artifactId>pusher-http-java</artifactId>

<version>1.0.0</version>

</dependency>

<dependency>

<groupId>com.google.guava</groupId>

<artifactId>guava</artifactId>

<version>20.0</version>

</dependency>

<dependency>

<groupId>com.fasterxml.jackson.core</groupId>

<artifactId>jackson-databind</artifactId>

<version>2.8.8</version>

</dependency>

<dependency>

<groupId>javax.servlet</groupId>

<artifactId>servlet-api</artifactId>

<version>2.5</version>

<scope>provided</scope>

</dependency>

<dependency>

<groupId>com.google.appengine</groupId>

<artifactId>appengine-api-1.0-sdk</artifactId>

<version>1.9.54</version>

</dependency>

</dependencies>

<build>

<!-- for hot reload of the web application -->

<outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/classes</outputDirectory>

<plugins>

<plugin>

<groupId>com.google.cloud.tools</groupId>

<artifactId>appengine-maven-plugin</artifactId>

<version>1.3.1</version>

</plugin>

</plugins>

</build>

</project>

package com.example.appengine.pusher;

import com.google.appengine.api.users.User;

import com.google.appengine.api.users.UserServiceFactory;

import com.google.common.io.CharStreams;

import com.pusher.rest.Pusher;

import com.pusher.rest.data.PresenceUser;

import java.io.IOException;

import java.io.UnsupportedEncodingException;

import java.net.URLDecoder;

import java.util.HashMap;

import java.util.Map;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class AuthorizeServlet extends HttpServlet {

@Override

public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {

// Instantiate a pusher connection

Pusher pusher = PusherService.getDefaultInstance();

// Get current logged in user credentials

User user = UserServiceFactory.getUserService().getCurrentUser();

// redirect to homepage if user is not authorized

if (user == null) {

response.sendRedirect("/");

return;

}

String currentUserId = user.getUserId();

String displayName = user.getNickname().replaceFirst("@.*", "");

String query = CharStreams.toString(request.getReader());

// socket_id, channel_name parameters are automatically set in the POST body of the request

// eg.socket_id=1232.12&channel_name=presence-my-channel

Map<String, String> data = splitQuery(query);

String socketId = data.get("socket_id");

String channelId = data.get("channel_name");

// Presence channels (presence-*) require user identification for authentication

Map<String, String> userInfo = new HashMap<>();

userInfo.put("displayName", displayName);

// Inject custom authentication code for your application here to allow /deny current request

String auth =

pusher.authenticate(socketId, channelId, new PresenceUser(currentUserId, userInfo));

// if successful, returns authorization in the format

// {

// "auth":"49e26cb8e9dde3dfc009:a8cf1d3deefbb1bdc6a9d1547640d49d94b4b512320e2597c257a740edd1788f",

// "channel_data":"{\"user_id\":\"23423435252\",\"user_info\":{\"displayName\":\"John Doe\"}}"

// }

response.getWriter().append(auth);

}

private static Map<String, String> splitQuery(String query) throws UnsupportedEncodingException {

Map<String, String> query_pairs = new HashMap<>();

String[] pairs = query.split("&");

for (String pair : pairs) {

int idx = pair.indexOf("=");

query_pairs.put(

URLDecoder.decode(pair.substring(0, idx), "UTF-8"),

URLDecoder.decode(pair.substring(idx + 1), "UTF-8"));

}

return query_pairs;

}

}

package com.example.appengine.pusher;

import com.google.appengine.api.users.User;

import com.google.appengine.api.users.UserService;

import com.google.appengine.api.users.UserServiceFactory;

import java.io.IOException;

import java.net.URI;

import java.net.URISyntaxException;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class ChatServlet extends HttpServlet {

public static String getUriWithChatRoom(HttpServletRequest request, String chatRoom) {

try {

String query = "";

if (chatRoom != null) {

query = "room=" + chatRoom;

}

URI thisUri = new URI(request.getRequestURL().toString());

URI uriWithOptionalRoomParam =

new URI(

thisUri.getScheme(),

thisUri.getUserInfo(),

thisUri.getHost(),

thisUri.getPort(),

"/",

query,

"");

return uriWithOptionalRoomParam.toString();

} catch (URISyntaxException e) {

throw new RuntimeException(e);

}

}

@Override

public void doGet(HttpServletRequest req, HttpServletResponse resp)

throws ServletException, IOException {

final UserService userService = UserServiceFactory.getUserService();

User currentUser = userService.getCurrentUser();

String room = req.getParameter("room");

// Show login link if user is not logged in.

if (currentUser == null) {

String loginUrl = userService.createLoginURL(getUriWithChatRoom(req, room));

resp.getWriter().println("<p>Please <a href=\"" + loginUrl + "\">sign in</a>.</p>");

return;

}

// user is already logged in

if (room != null) {

req.setAttribute("room", room);

}

getServletContext().getRequestDispatcher("/WEB-INF/view/chat.jsp").forward(req, resp);

}

}

package com.example.appengine.pusher;

import com.pusher.rest.Pusher;

public abstract class PusherService {

public static final String APP_KEY = System.getenv("PUSHER_APP_KEY");

public static final String CLUSTER = System.getenv("PUSHER_CLUSTER");

private static final String APP_ID = System.getenv("PUSHER_APP_ID");

private static final String APP_SECRET = System.getenv("PUSHER_APP_SECRET");

private static Pusher instance;

static Pusher getDefaultInstance() {

if (instance != null) {

return instance;

} // Instantiate a pusher

Pusher pusher = new Pusher(APP_ID, APP_KEY, APP_SECRET);

pusher.setCluster(CLUSTER); // required, if not default mt1 (us-east-1)

pusher.setEncrypted(true); // optional, ensure subscriber also matches these settings

instance = pusher;

return pusher;

}

}