Add GAE standard + firebase tictactoe sample

appengine/firebase-tictactoe/README.md

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+# Tic Tac Toe on Google App Engine Standard using Firebase
+
+This directory contains a project that implements a realtime two-player game of
+Tic Tac Toe on Google [App Engine Standard][standard], using the [Firebase] database
+for realtime notifications when the board changes.
+
+[Firebase]: https://firebase.google.com
+[standard]: https://cloud.google.com/appengine/docs/about-the-standard-environment
+
+## Prerequisites
+
+* Install [Apache Maven][maven] 3.0.5 or later
+* Create a project in the [Firebase Console][fb-console]
+* Install the [Google Cloud SDK][sdk]
+* For staging locally, you must supply credentials that would otherwise be
+  inferred from the App Engine environment. Download [service account
+  credentials][creds] and set the `GOOGLE_APPLICATION_CREDENTIALS` environment
+  variable to its path:
+
+        export GOOGLE_APPLICATION_CREDENTIALS=/path/to/your/credentials.json
+
+* In the [Overview section][fb-overview] of the Firebase console, click 'Add
+  Firebase to your web app' and replace the contents of the file
+  `src/main/webapp/WEB-INF/view/firebase_config.jspf` with that code snippet.
+* Edit
+  [`src/main/webapp/WEB-INF/appengine-web.xml`](src/main/webapp/WEB-INF/appengine-web.xml)
+  and replace `_your_app_id_here_` with your project id.
+
+[fb-console]: https://console.firebase.google.com
+[sdk]: https://cloud.google.com/sdk
+[creds]: https://console.firebase.google.com/iam-admin/serviceaccounts/project?project=_&consoleReturnUrl=https:%2F%2Fconsole.firebase.google.com%2Fproject%2F_%2Fsettings%2Fgeneral%2F
+[fb-overview]: https://console.firebase.google.com/project/_/overview
+
+
+## Run the sample
+
+* To run the app locally:
+
+    ```sh
+    $ mvn appengine:run
+    ```
+
+## Troubleshooting
+
+* If you see the error `Google Cloud SDK path was not provided ...`:
+    * Make sure you've installed the [Google cloud SDK][sdk]
+    * You may have installed it in a non-standard path. In that case, set the
+      environment variable `GOOGLE_CLOUD_SDK_HOME` to point to where you
+      installed the SDK:
+
+        ```sh
+        export GOOGLE_CLOUD_SDK_HOME=/path/to/google-cloud-sdk
+        ```
+
+## Contributing changes
+
+See [CONTRIBUTING.md](../../CONTRIBUTING.md).
+
+## Licensing
+
+See [LICENSE](../../LICENSE).
+

appengine/firebase-tictactoe/pom.xml

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+<!--
+ Copyright 2015 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.
+-->
+<project>
+    <modelVersion>4.0.0</modelVersion>
+    <packaging>war</packaging>
+    <version>1.0-SNAPSHOT</version>
+    <groupId>com.example.appengine</groupId>
+    <artifactId>appengine-firebase</artifactId>
+    <parent>
+        <groupId>com.google.cloud</groupId>
+        <artifactId>doc-samples</artifactId>
+        <version>1.0.0</version>
+        <relativePath>../..</relativePath>
+    </parent>
+    <properties>
+        <objectify.version>5.1.13</objectify.version>
+    </properties>
+    <!-- [START set_versions] -->
+    <prerequisites>
+        <maven>3.3.9</maven>
+    </prerequisites>
+    <!-- [END set_versions] -->
+    <dependencies>
+        <dependency>
+            <groupId>com.google.appengine</groupId>
+            <artifactId>appengine-api-1.0-sdk</artifactId>
+            <version>${appengine.sdk.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>javax.servlet</groupId>
+            <artifactId>servlet-api</artifactId>
+            <version>2.5</version>
+            <type>jar</type>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.json</groupId>
+            <artifactId>json</artifactId>
+            <version>20160810</version>
+        </dependency>
+        <dependency>
+            <groupId>com.googlecode.objectify</groupId>
+            <artifactId>objectify</artifactId>
+            <version>${objectify.version}</version>
+        </dependency>
+        <dependency>
+          <groupId>com.google.guava</groupId>
+          <artifactId>guava</artifactId>
+          <version>19.0</version>
+        </dependency>
+        <dependency>
+          <groupId>com.google.api-client</groupId>
+          <artifactId>google-api-client-appengine</artifactId>
+          <version>1.22.0</version>
+        </dependency>
+
+
+        <!-- Test Dependencies -->
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-all</artifactId>
+            <version>1.10.19</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.appengine</groupId>
+            <artifactId>appengine-testing</artifactId>
+            <version>${appengine.sdk.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.appengine</groupId>
+            <artifactId>appengine-api-stubs</artifactId>
+            <version>${appengine.sdk.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.appengine</groupId>
+            <artifactId>appengine-tools-sdk</artifactId>
+            <version>${appengine.sdk.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.truth</groupId>
+            <artifactId>truth</artifactId>
+            <version>0.30</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+    <build>
+        <!-- for hot reload of the web application -->
+        <outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/classes
+        </outputDirectory>
+        <plugins>
+            <plugin>
+                <groupId>com.google.cloud.tools</groupId>
+                <artifactId>appengine-maven-plugin</artifactId>
+                <version>1.0.0</version>
+            </plugin>
+        </plugins>
+    </build>
+</project>

appengine/firebase-tictactoe/src/main/java/com/example/appengine/firetactoe/DeleteServlet.java

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+/*
+ * 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.firetactoe;
+
+import com.google.appengine.api.users.UserService;
+import com.google.appengine.api.users.UserServiceFactory;
+import com.googlecode.objectify.Objectify;
+import com.googlecode.objectify.ObjectifyService;
+
+import java.io.IOException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+public class DeleteServlet extends HttpServlet {
+  @Override
+  public void doPost(HttpServletRequest req, HttpServletResponse resp)
+      throws IOException {
+    String gameId = req.getParameter("gameKey");
+    Objectify ofy = ObjectifyService.ofy();
+    Game game = ofy.load().type(Game.class).id(gameId).safe();
+
+    UserService userService = UserServiceFactory.getUserService();
+    String currentUserId = userService.getCurrentUser().getUserId();
+
+    game.deleteChannel(currentUserId);
+  }
+}

appengine/firebase-tictactoe/src/main/java/com/example/appengine/firetactoe/FirebaseChannel.java

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+/*
+ * 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.firetactoe;
+
+import com.google.api.client.extensions.appengine.http.UrlFetchTransport;
+import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
+import com.google.api.client.http.ByteArrayContent;
+import com.google.api.client.http.GenericUrl;
+import com.google.api.client.http.HttpRequestFactory;
+import com.google.api.client.http.HttpResponse;
+import com.google.api.client.http.HttpTransport;
+import com.google.appengine.api.appidentity.AppIdentityService;
+import com.google.appengine.api.appidentity.AppIdentityServiceFactory;
+import com.google.common.io.BaseEncoding;
+import com.google.common.io.CharStreams;
+
+import org.json.JSONObject;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Map;
+
+public class FirebaseChannel {
+  private static final String FIREBASE_SNIPPET_PATH = "WEB-INF/view/firebase_config.jspf";
+  private static final Collection FIREBASE_SCOPES = Arrays.asList(
+      "https://www.googleapis.com/auth/firebase.database",
+      "https://www.googleapis.com/auth/userinfo.email"
+  );
+  private static final String IDENTITY_ENDPOINT =
+      "https://identitytoolkit.googleapis.com/google.identity.identitytoolkit.v1.IdentityToolkit";
+  static final HttpTransport HTTP_TRANSPORT = new UrlFetchTransport();
+
+  private String firebaseDbUrl;
+  private GoogleCredential credential;
+
+  private static FirebaseChannel instance;
+
+  public static FirebaseChannel getInstance() {
+    if (instance == null) {
+      instance = new FirebaseChannel();
+    }
+    return instance;
+  }
+
+  private FirebaseChannel() {
+    try {
+      String firebaseSnippet = CharStreams.toString(
+          new InputStreamReader(new FileInputStream(FIREBASE_SNIPPET_PATH)));
+      firebaseDbUrl = parseFirebaseUrl(firebaseSnippet);
+
+      credential = GoogleCredential.getApplicationDefault().createScoped(FIREBASE_SCOPES);
+    } catch (Exception e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+  private static String parseFirebaseUrl(String firebaseSnippet) {
+    int idx = firebaseSnippet.indexOf("databaseURL");
+    if (-1 == idx) {
+      throw new RuntimeException(
+          "Please copy your Firebase web snippet into " + FIREBASE_SNIPPET_PATH);
+    }
+    idx = firebaseSnippet.indexOf(':', idx);
+    int openQuote = firebaseSnippet.indexOf('"', idx);
+    int closeQuote = firebaseSnippet.indexOf('"', openQuote + 1);
+    return firebaseSnippet.substring(openQuote + 1, closeQuote);
+  }
+
+  public void sendFirebaseMessage(String channelKey, Game game)
+      throws IOException {
+    // Make requests auth'ed using Application Default Credentials
+    HttpRequestFactory requestFactory = HTTP_TRANSPORT.createRequestFactory(credential);
+    GenericUrl url = new GenericUrl(
+        String.format("%s/channels/%s.json", firebaseDbUrl, channelKey));
+    HttpResponse response = null;
+
+    try {
+      if (null == game) {
+        response = requestFactory.buildDeleteRequest(url).execute();
+      } else {
+        String gameJson = game.getMessageString();
+        response = requestFactory.buildPatchRequest(
+            url, new ByteArrayContent("application/json", gameJson.getBytes())).execute();
+      }
+
+      if (response.getStatusCode() != 200) {
+        throw new RuntimeException(
+            "Error code while updating Firebase: " + response.getStatusCode());
+      }
+
+    } finally {
+      if (null != response) {
+        response.disconnect();
+      }
+    }
+  }
+
+  /**
+   * Create a secure JWT token for the given userId.
+   */
+  public String createFirebaseToken(Game game, String userId) {
+    final AppIdentityService appIdentity = AppIdentityServiceFactory.getAppIdentityService();
+    final BaseEncoding base64 = BaseEncoding.base64();
+
+    String header = base64.encode("{\"typ\":\"JWT\",\"alg\":\"RS256\"}".getBytes());
+
+    // Construct the claim
+    String channelKey = game.getChannelKey(userId);
+    String clientEmail = appIdentity.getServiceAccountName();
+    long epochTime = System.currentTimeMillis() / 1000;
+    long expire = epochTime + 60 * 60; // an hour from now
+
+    Map<String, Object> claims = new HashMap<String, Object>();
+    claims.put("iss", clientEmail);
+    claims.put("sub", clientEmail);
+    claims.put("aud", IDENTITY_ENDPOINT);
+    claims.put("uid", channelKey);
+    claims.put("iat", epochTime);
+    claims.put("exp", expire);
+
+    String payload = base64.encode(new JSONObject(claims).toString().getBytes());
+    String toSign = String.format("%s.%s", header, payload);
+    AppIdentityService.SigningResult result = appIdentity.signForApp(toSign.getBytes());
+    return String.format("%s.%s", toSign, base64.encode(result.getSignature()));
+  }
+}