Adding App Engine pull task queue sample

appengine/taskqueue/pull/README.md

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+# Pull Task Queue sample for Google App Engine
+
+This sample demonstrates how to use [pull task queues][appid] on [Google App
+Engine][ae-docs].
+
+[appid]: https://cloud.google.com/appengine/docs/java/taskqueue/overview-pull
+[ae-docs]: https://cloud.google.com/appengine/docs/java/
+
+## Running locally 
+This example uses the
+[Maven gcloud plugin](https://cloud.google.com/appengine/docs/java/managed-vms/maven).
+To run this sample locally:
+
+    $ mvn appengine:devserver
+
+## Deploying
+In the following command, replace YOUR-PROJECT-ID with your
+[Google Cloud Project ID](https://developers.google.com/console/help/new/#projectnumber).
+
+    $ mvn appengine:update -Dappengine.appId=YOUR-PROJECT-ID -Dappengine.version=SOME-VERSION
+
+## Setup
+To save your project settings so that you don't need to enter the
+ parameters, you can:
+
+1. Update the <application> tag in src/main/webapp/WEB-INF/appengine-web.xml
+   with your project name.
+
+2. Update the <version> tag in src/main/webapp/WEB-INF/appengine-web.xml
+   with a valid version number.
+
+
+You will now be able to run
+
+    $ mvn appengine:update
+
+without the need for any additional parameters.

appengine/taskqueue/pull/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+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.
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <packaging>war</packaging>
+    <version>1.0-SNAPSHOT</version>
+    <groupId>com.example.taskqueue</groupId>
+    <artifactId>taskqueue</artifactId>
+
+    <parent>
+      <artifactId>doc-samples</artifactId>
+      <groupId>com.google.cloud</groupId>
+      <version>1.0.0</version>
+      <relativePath>../../..</relativePath>
+    </parent>
+    <dependencies>
+        <!-- Compile/runtime dependencies -->
+        <dependency>
+            <groupId>com.google.appengine</groupId>
+            <artifactId>appengine-api-1.0-sdk</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>javax.servlet</groupId>
+            <artifactId>servlet-api</artifactId>
+            <version>2.5</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>jstl</groupId>
+            <artifactId>jstl</artifactId>
+            <version>1.2</version>
+        </dependency>
+
+        <!-- Test Dependencies -->
+        <dependency>
+            <groupId>com.google.appengine</groupId>
+            <artifactId>appengine-testing</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.appengine</groupId>
+            <artifactId>appengine-api-stubs</artifactId>
+            <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>org.codehaus.mojo</groupId>
+                <artifactId>versions-maven-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <phase>compile</phase>
+                        <goals>
+                            <goal>display-dependency-updates</goal>
+                            <goal>display-plugin-updates</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>1.7</source>
+                    <target>1.7</target>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>com.google.appengine</groupId>
+                <artifactId>appengine-maven-plugin</artifactId>
+                <version>${appengine.sdk.version}</version>
+            </plugin>
+            <plugin>
+              <groupId>com.google.appengine</groupId>
+              <artifactId>gcloud-maven-plugin</artifactId>
+              <version>${appengine.sdk.version}</version>
+              <configuration>
+                <set_default>true</set_default>
+              </configuration>
+            </plugin>
+        </plugins>
+    </build>
+</project>

appengine/taskqueue/pull/src/main/java/com/example/taskqueue/TaskqueueServlet.java

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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.
+ */
+
+package com.example.taskqueue;
+
+import com.google.appengine.api.taskqueue.TaskOptions;
+import com.google.appengine.api.taskqueue.Queue;
+import com.google.appengine.api.taskqueue.QueueFactory;
+import com.google.appengine.api.taskqueue.TaskHandle;
+
+import java.io.IOException;
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import java.util.Date;
+import java.util.List;
+import java.util.logging.Logger;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Form Handling Servlet
+ * This servlet has one method
+ * {@link #doPost(<#HttpServletRequest req#>, <#HttpServletResponse resp#>)} which takes the form
+ * submisson from /src/main/webapp/tasks.jsp to add and delete tasks.
+ */
+public class TaskqueueServlet extends HttpServlet {
+
+   private static final Logger log = Logger.getLogger(TaskqueueServlet.class.getName());
+   private static final int numberOfTasksToAdd = 100;
+   private static final int numberOfTasksToLease = 100;
+   private static boolean useTaggedTasks = true;
+   private static String output;
+   private static String message;
+
+   // Process the http POST of the form
+   @Override
+   public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException,
+       ServletException {
+       if (req.getParameter("addTask") != null) {
+         String content = req.getParameter("content");
+         String output = String.format("Adding %d Tasks to the Task Queue with a payload of '%s'",
+           numberOfTasksToAdd, content.toString());
+         log.info(output.toString());
+
+         // Add Tasks to Task Queue
+         // [START get_queue]
+         Queue q = QueueFactory.getQueue("pull-queue");
+         // [END get_queue]
+         if (!useTaggedTasks) {
+           for (int i = 0; i < numberOfTasksToAdd; i++) {
+              // [START add_task]
+      	      q.add(TaskOptions.Builder.withMethod(TaskOptions.Method.PULL)
+                                                   .payload(content.toString()));
+              // [END add_task]
+           }
+         } else {
+           for (int i = 0; i < numberOfTasksToAdd; i++) {
+              // [START add_task_w_tag]
+              q.add(TaskOptions.Builder.withMethod(TaskOptions.Method.PULL)
+                                                .payload(content.toString())
+                                                .tag("process".getBytes()));
+              // [END add_task_w_tag]
+
+           }
+         }
+         try {
+           message = "Added " + numberOfTasksToAdd + " tasks to the task queue.";
+           req.setAttribute("message", message);
+           req.getRequestDispatcher("tasks.jsp").forward(req,resp);
+         } catch (ServletException e) {
+           throw new ServletException("ServletException error: ", e);
+         }
+       } else if (req.getParameter("leaseTask") != null) {
+         output = String.format("Pulling %d Tasks from the Task Queue", numberOfTasksToLease);
+         log.info(output.toString());
+
+         // Pull tasks from the Task Queue and process them
+         Queue q = QueueFactory.getQueue("pull-queue");
+         if (!useTaggedTasks) {
+           // [START lease_tasks]
+           List<TaskHandle> tasks = q.leaseTasks(3600, TimeUnit.SECONDS, numberOfTasksToLease);
+           // [END lease_tasks]
+           message = processTasks(tasks, q);
+         } else {
+           // [START lease_tasks_by_tag]
+           // Lease only tasks tagged with "process"
+           List<TaskHandle> tasks = q.leaseTasksByTag(3600, TimeUnit.SECONDS, numberOfTasksToLease, "process");
+           // You can also specify a tag to lease via LeaseOptions passed to leaseTasks.
+           // [END lease_tasks_by_tag]
+           message = processTasks(tasks, q);
+         }
+       req.setAttribute("message", message);
+       req.getRequestDispatcher("tasks.jsp").forward(req,resp);
+      } else {
+        resp.sendRedirect("/");
+      }
+   }
+
+   //Method to process and delete tasks
+   private static String processTasks(List<TaskHandle> tasks, Queue q) {
+     String payload;
+     int numberOfDeletedTasks = 0;
+     for (TaskHandle task : tasks) {
+       payload = new String(task.getPayload());
+       output = String.format("Processing: taskName='%s'  payload='%s'", task.getName()
+         .toString(), payload.toString());
+       log.info(output.toString());
+       output = String.format("Deleting taskName='%s'", task.getName().toString());
+       log.info(output.toString());
+       // [START delete_task]
+       q.deleteTask(task);
+       // [END delete_task]
+       numberOfDeletedTasks++;
+     }
+     if (numberOfDeletedTasks > 0) {
+       message = "Processed and deleted " + numberOfTasksToLease + " tasks from the " +
+         " task queue.";
+     } else {
+       message = "Task Queue has no tasks available for lease.";
+     }
+     return message;
+   }
+}

appengine/taskqueue/pull/src/main/webapp/WEB-INF/appengine-web.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<!-- [START_EXCLUDE] -->
+<!--
+  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.
+-->
+<!-- [END_EXCLUDE] -->
+<appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
+  <application>YOUR-PROJECT-ID</application>
+  <version>YOUR-VERSION-ID</version>
+  <threadsafe>true</threadsafe>
+</appengine-web-app>

appengine/taskqueue/pull/src/main/webapp/WEB-INF/logging.properties

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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.
+
+# A default java.util.logging configuration.
+# (All App Engine logging is through java.util.logging by default).
+#
+# To use this configuration, copy it into your application's WEB-INF
+# folder and add the following to your appengine-web.xml:
+# 
+# <system-properties>
+#   <property name="java.util.logging.config.file" value="WEB-INF/logging.properties"/>
+# </system-properties>
+#
+
+# Set the default logging level for all loggers to WARNING
+.level = INFO

appengine/taskqueue/pull/src/main/webapp/WEB-INF/queue.xml

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+<queue-entries>
+  <queue>
+    <name>pull-queue</name>
+    <mode>pull</mode>
+    <acl>
+      <user-email>[email protected]</user-email>      <!-- can list, get, lease, delete, and update tasks -->
+      <writer-email>[email protected]</writer-email>  <!--  can insert tasks, in addition to rights granted by being a user_email above -->
+    </acl>
+  </queue>
+</queue-entries>

appengine/taskqueue/pull/src/main/webapp/WEB-INF/web.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<!-- [START_EXCLUDE] -->
+<!--
+  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.
+-->
+<!-- [END_EXCLUDE] -->
+<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" 
+  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
+  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
+  http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
+   <servlet>
+      <servlet-name>taskqueue</servlet-name>
+      <servlet-class>com.example.taskqueue.TaskqueueServlet</servlet-class>
+    </servlet>
+
+    <servlet-mapping>
+      <servlet-name>taskqueue</servlet-name>
+      <url-pattern>/taskqueue</url-pattern>
+    </servlet-mapping>
+
+    <welcome-file-list>
+        <welcome-file>tasks.jsp</welcome-file>
+    </welcome-file-list>
+</web-app>