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Add Cloud Tasks Samples (#930)
* Added Cloud Tasks snippets for Pull Queues. * Added AppEngine Flexible App for Cloud Tasks API. * Minor text fixes.
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‎cloud-tasks/README.md

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# Google Cloud Tasks Pull Queue Samples
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Sample command-line program for interacting with the Google Cloud Tasks
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API using pull queues.
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Pull queues let you add tasks to a queue, then programatically remove
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and interact with them. Tasks can be added or processed in any
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environment, such as on Google App Engine or Google Compute Engine.
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`PullQueue.java` is a simple command-line program to demonstrate listing
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queues, creating tasks, and pulling and acknowledging tasks.
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## Initial Setup
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* Set up a Google Cloud Project and enable billing.
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* Enable the
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[Cloud Tasks API](https://console.cloud.google.com/launcher/details/google/cloudtasks.googleapis.com).
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* Download and install the [Cloud SDK](https://cloud.google.com/sdk).
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* Download and install [Maven](http://maven.apache.org/install.html).
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## Creating a queue
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To create a queue using the Cloud SDK, use the following gcloud command:
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```bash
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gcloud alpha tasks queues create-pull-queue my-pull-queue
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```
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In this example, the queue will be named `my-pull-queue`.
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## Running the Samples
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From the project folder, build your project with:
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```
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mvn clean assembly:single
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```
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Optionally, you can set up your settings as environment variables:
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```
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export PROJECT_ID=<YOUR_PROJECT_ID>
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export LOCATION_ID=<YOUR_ZONE>
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export QUEUE_ID=<YOUR_QUEUE_NAME>
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```
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Next, create a task for a queue:
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```
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java -cp target/cloudtasks-1.0.0-jar-with-dependencies.jar \
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com.example.PullQueue create-task --project=$PROJECT_ID --location=$LOCATION_ID --queue=$QUEUE_ID
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```
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Finally, pull and acknowledge a task:
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```
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java -cp target/cloudtasks-1.0.0-jar-with-dependencies.jar \
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com.example.PullQueue pull-and-ack-task --project=$PROJECT_ID --location=$LOCATION_ID --queue=$QUEUE_ID
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```
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Note that usually, there would be a processing step in between pulling a task and acknowledging it.
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‎cloud-tasks/pom.xml

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<?xml version="1.0" encoding="UTF-8"?>
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<!--
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Copyright 2017 Google Inc.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<project>
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<modelVersion>4.0.0</modelVersion>
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<groupId>com.example</groupId>
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<artifactId>cloudtasks</artifactId>
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<version>1.0.0</version>
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<parent>
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<artifactId>doc-samples</artifactId>
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<groupId>com.google.cloud</groupId>
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<version>1.0.0</version>
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<relativePath>..</relativePath>
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</parent>
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<dependencies>
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<dependency>
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<groupId>com.google.apis</groupId>
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<artifactId>google-api-services-cloudtasks</artifactId>
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<version>v2beta2-rev16-1.23.0</version>
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</dependency>
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<dependency>
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<groupId>com.google.api-client</groupId>
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<artifactId>google-api-client</artifactId>
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<version>1.23.0</version>
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</dependency>
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<dependency>
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<groupId>com.google.http-client</groupId>
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<artifactId>google-http-client-jackson2</artifactId>
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<version>1.23.0</version>
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</dependency>
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<!-- parser dependency -->
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<dependency>
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<groupId>net.sourceforge.argparse4j</groupId>
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<artifactId>argparse4j</artifactId>
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<version>0.8.1</version>
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</dependency>
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<!-- test dependencies -->
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<dependency>
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<groupId>junit</groupId>
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<artifactId>junit</artifactId>
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<version>4.12</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>com.google.truth</groupId>
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<artifactId>truth</artifactId>
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<version>0.36</version>
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<scope>test</scope>
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</dependency>
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</dependencies>
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<build>
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<sourceDirectory>src/main/java</sourceDirectory>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-compiler-plugin</artifactId>
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<version>3.2</version>
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</plugin>
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<plugin>
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<artifactId>maven-assembly-plugin</artifactId>
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<configuration>
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<descriptorRefs>
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<descriptorRef>jar-with-dependencies</descriptorRef>
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</descriptorRefs>
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</configuration>
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</plugin>
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</plugins>
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</build>
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</project>

‎cloud-tasks/src/main/java/com.example.cloudtasks/PullQueue.java

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/**
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* Copyright 2017 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.cloudtasks;
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import com.google.api.services.cloudtasks.v2beta2.CloudTasks;
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import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
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import com.google.api.client.http.HttpTransport;
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import com.google.api.client.http.javanet.NetHttpTransport;
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import com.google.api.client.json.JsonFactory;
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import com.google.api.client.json.jackson2.JacksonFactory;
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import com.google.api.services.cloudtasks.v2beta2.CloudTasksScopes;
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import com.google.api.services.cloudtasks.v2beta2.model.AcknowledgeTaskRequest;
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import com.google.api.services.cloudtasks.v2beta2.model.CreateTaskRequest;
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import com.google.api.services.cloudtasks.v2beta2.model.PullMessage;
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import com.google.api.services.cloudtasks.v2beta2.model.PullTasksRequest;
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import com.google.api.services.cloudtasks.v2beta2.model.PullTasksResponse;
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import com.google.api.services.cloudtasks.v2beta2.model.Task;
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import com.google.common.io.BaseEncoding;
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import java.io.IOException;
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import net.sourceforge.argparse4j.ArgumentParsers;
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import net.sourceforge.argparse4j.inf.ArgumentParser;
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import net.sourceforge.argparse4j.inf.Namespace;
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import net.sourceforge.argparse4j.inf.Subparsers;
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public class PullQueue {
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/**
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* Creates an authorized CloudTasks client service using Application Default Credentials.
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*
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* @return an authorized CloudTasks client
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* @throws IOException if there's an error getting the default credentials.
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*/
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private static CloudTasks createAuthorizedClient() throws IOException {
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// Create the credential
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HttpTransport transport = new NetHttpTransport();
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JsonFactory jsonFactory = new JacksonFactory();
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// Authorize the client using Application Default Credentials
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// @see https://g.co/dv/identity/protocols/application-default-credentials
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GoogleCredential credential = GoogleCredential.getApplicationDefault(transport, jsonFactory);
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// Depending on the environment that provides the default credentials (e.g. Compute Engine, App
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// Engine), the credentials may require us to specify the scopes we need explicitly.
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// Check for this case, and inject the scope if required.
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if (credential.createScopedRequired()) {
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credential = credential.createScoped(CloudTasksScopes.all());
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}
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return new CloudTasks.Builder(transport, jsonFactory, credential)
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.setApplicationName("Cloud Tasks Snippets")
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.build();
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}
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/**
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* Create a task for a given queue with a given payload.
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*/
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private static Task createTask(
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String project, String location, String queue) throws IOException {
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// The name of the queue to use
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String queueName = String.format(
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"projects/%s/locations/%s/queues/%s", project, location, queue);
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// Create the Cloud Tasks Client
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CloudTasks client = createAuthorizedClient();
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// Create the Task to put in the Queue
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String message = "a message for the recipient";
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String payload = BaseEncoding.base64().encode(message.getBytes());
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Task task = new Task().setPullMessage(new PullMessage().setPayload(payload));
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// Create the CreateTaskRequest
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CreateTaskRequest request = new CreateTaskRequest().setTask(task);
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//Execute the request and return the created Task
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Task result = client
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.projects()
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.locations()
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.queues()
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.tasks()
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.create(queueName, request)
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.execute();
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System.out.println(String.format("Created task %s",task.getName()));
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return result;
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}
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/**
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* Pull a single task from a given queue and lease it for 10 minutes.
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*/
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private static Task pullTask(
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String project, String location, String queue) throws IOException {
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// The name of the queue to use
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String queueName = String.format(
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"projects/%s/locations/%s/queues/%s", project, location, queue);
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// Create the Cloud Tasks Client
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CloudTasks client = createAuthorizedClient();
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// Create the PullTasksRequest
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PullTasksRequest request = new PullTasksRequest().setMaxTasks(1).setLeaseDuration("600s");
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//Execute the request and return the pulled task
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PullTasksResponse response = client
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.projects()
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.locations()
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.queues()
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.tasks()
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.pull(queueName, request)
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.execute();
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return response.getTasks().get(0);
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}
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/**
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* Acknowledge a given task, which removes it from the queue.
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*/
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private static void acknowledgeTask(Task task) throws IOException{
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// Create the Cloud Tasks Client
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CloudTasks client = createAuthorizedClient();
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// Create the AcknowledgeTaskRequest
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AcknowledgeTaskRequest request = new AcknowledgeTaskRequest()
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.setScheduleTime(task.getScheduleTime());
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//Execute the request
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client
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.projects()
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.locations()
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.queues()
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.tasks()
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.acknowledge(task.getName(), request)
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.execute();
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System.out.println(String.format("Acknowledged task %s", task.getName()));
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}
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public static void main(String[] args) throws Exception {
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ArgumentParser parser = ArgumentParsers.newFor("PullQueue").build()
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.defaultHelp(true)
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.description("Sample command-line program for interacting with the Cloud Tasks API.\n\n"
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+ "See README.md for instructions on setting up your development environment "
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+ "and running the scripts.");
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Subparsers subparsers = parser.addSubparsers().dest("command");
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// Create the parser for the command 'create-task'
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ArgumentParser createTaskParser = subparsers
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.addParser("create-task")
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.help("Acknowledge a given task, which removes it from the queue.");
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createTaskParser
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.addArgument("--project")
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.help("Project of the queue to add the task to.")
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.required(true);
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createTaskParser
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.addArgument("--location")
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.help("Location of the queue to add the task to.")
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.required(true);
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createTaskParser
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.addArgument("--queue")
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.help("ID (short name) of the queue to add the task to.")
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.required(true);
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// Create the parser for the command 'pull-and-ack-task'
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ArgumentParser pullAndAckParser = subparsers
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.addParser("pull-and-ack-task")
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.help("Create a task for a given queue with an arbitrary payload.");
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pullAndAckParser
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.addArgument("--project")
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.help("Project of the queue to add the task to.")
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.required(true);
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pullAndAckParser
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.addArgument("--location")
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.help("Location of the queue to add the task to.")
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.required(true);
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pullAndAckParser
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.addArgument("--queue")
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.help("ID (short name) of the queue to add the task to.")
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.required(true);
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// Parse commands
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Namespace cmd = parser.parseArgs(args);
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String command = cmd.get("command");
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String project = cmd.get("project");
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String queue = cmd.get("queue");
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String location = cmd.get("location");
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// Execute commands
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if(command.equals("create-task")){
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createTask(project, location, queue);
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}
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if(command.equals("pull-and-ask-task")){
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Task task = pullTask(project, location, queue);
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acknowledgeTask(task);
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}
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}
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}

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