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Adding Pub/Sub App engine Java 8 sample (#865)
* Adding Pub/Sub app engine sample * updating README * removing unit tests updating README based on review
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‎appengine-java8/pom.xml

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<module>postgres</module>
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<module>pubsub</module>
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<module>requests</module>
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<module>remote-client</module>

‎appengine-java8/pubsub/README.md

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# Using Google Cloud Pub/Sub on App Engine Standard Java 8 Environment
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This sample demonstrates how to use [Google Cloud Pub/Sub][pubsub]
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from [Google App Engine standard environment][ae-docs].
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[pubsub]: https://cloud.google.com/pubsub/docs/
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[ae-docs]: https://cloud.google.com/appengine/docs/java/
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The home page of this application provides a form to publish messages using Google/Cloud PubSub. The application
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then receives these published messages over a push subscription endpoint and then stores in Google Cloud Datastore.
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The home page provides a view of the most recent messages persisted in storage.
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## Clone the sample app
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Copy the sample apps to your local machine, and cd to the pubsub directory:
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```
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git clone https://github.com/GoogleCloudPlatform/java-docs-samples
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cd java-docs-samples/appengine-java8/pubsub
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```
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## Setup
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- Make sure [`gcloud`](https://cloud.google.com/sdk/docs/) is installed and initialized:
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```
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gcloud init
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```
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- If this is the first time you are creating an App Engine project
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```
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gcloud app create
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```
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- For local development, [set up](https://cloud.google.com/docs/authentication/getting-started) authentication
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- [Enable](https://console.cloud.google.com/launcher/details/google/pubsub.googleapis.com) Pub/Sub API
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- Create a topic
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```
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gcloud beta pubsub topics create <your-topic-name>
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```
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- Create a push subscription, to send messages to a Google Cloud Project URL such as https://<your-project-id>.appspot.com/push.
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The verification token is used to ensure that the end point only handles requests that are sent matching the verification token.
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You can use `uuidgen` on MacOS X, Windows, and Linux to generate a unique verification token.
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```
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gcloud beta pubsub subscriptions create <your-subscription-name> \
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--topic <your-topic-name> \
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--push-endpoint \
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https://<your-project-id>.appspot.com/pubsub/push?token=<your-verification-token> \
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--ack-deadline 30
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```
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## Run locally
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Set the following environment variables and run using shown Maven command. You can then
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direct your browser to `http://localhost:8080/`
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```
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export PUBSUB_TOPIC=<your-topic-name>
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export PUBSUB_VERIFICATION_TOKEN=<your-verification-token>
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mvn appengine:run
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```
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## Send fake subscription push messages with:
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```
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curl -H "Content-Type: application/json" -i --data @sample_message.json
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"localhost:8080/pubsub/push?token=<your-token>"
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```
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## Deploy
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Update the environment variables `PUBSUB_TOPIC` and `PUBSUB_VERIFICATION_TOKEN` in
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[`appengine-web.xml`](src/main/webapp/WEB-INF/appengine-web.xml),
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then:
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```
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mvn appengine:deploy
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```
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Direct your browser to `https://project-id.appspot.com`.

‎appengine-java8/pubsub/pom.xml

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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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<!-- [START project] -->
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<project>
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<modelVersion>4.0.0</modelVersion>
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<packaging>war</packaging>
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<version>1.0-SNAPSHOT</version>
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<groupId>com.example.flexible</groupId>
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<artifactId>appengine-pubsub</artifactId>
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<parent>
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<artifactId>appengine-java8-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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<properties>
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<maven.compiler.target>1.8</maven.compiler.target>
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<maven.compiler.source>1.8</maven.compiler.source>
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<failOnMissingWebXml>false</failOnMissingWebXml> <!-- REQUIRED -->
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<appengine.maven.plugin>1.3.1</appengine.maven.plugin>
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<jetty>9.4.4.v20170414</jetty>
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</properties>
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<dependencies>
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<dependency>
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<groupId>javax.servlet</groupId>
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<artifactId>javax.servlet-api</artifactId>
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<version>3.1.0</version>
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<type>jar</type>
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<scope>provided</scope>
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</dependency>
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<!-- [START dependencies] -->
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<dependency>
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<groupId>com.google.cloud</groupId>
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<artifactId>google-cloud-pubsub</artifactId>
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<version>0.24.0-beta</version>
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</dependency>
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<dependency>
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<groupId>com.google.cloud</groupId>
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<artifactId>google-cloud-datastore</artifactId>
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<version>1.6.0</version>
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</dependency>
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<!-- [END dependencies] -->
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</dependencies>
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<build>
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<!-- for hot reload of the web application -->
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<outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/classes</outputDirectory>
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<plugins>
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<plugin>
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<groupId>com.google.cloud.tools</groupId>
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<artifactId>appengine-maven-plugin</artifactId>
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<version>${appengine.maven.plugin}</version>
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<configuration>
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<!-- deploy configuration -->
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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>
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<!-- [END project] -->

‎appengine-java8/pubsub/sample_message.json

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{"message":{"data":"dGVzdA==","attributes":{},"messageId":"91010751788941","publishTime":"2017-09-25T23:16:42.302Z"}}

‎appengine-java8/pubsub/src/main/java/com/example/appengine/pubsub/Message.java

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/**
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* Copyright 2017 Google Inc.
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*
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* <p>Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of the License at
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*
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* <p>http://www.apache.org/licenses/LICENSE-2.0
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*
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* <p>Unless required by applicable law or agreed to in writing, software distributed under the
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* License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
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* express or implied. 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.appengine.pubsub;
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/**
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* A message captures information from the Pubsub message received over the push endpoint and is
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* persisted in storage.
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*/
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public class Message {
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private String messageId;
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private String publishTime;
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private String data;
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public Message(String messageId) {
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this.messageId = messageId;
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}
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public String getMessageId() {
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return messageId;
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}
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public void setMessageId(String messageId) {
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this.messageId = messageId;
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}
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public String getPublishTime() {
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return publishTime;
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}
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public void setPublishTime(String publishTime) {
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this.publishTime = publishTime;
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}
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public String getData() {
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return data;
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}
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public void setData(String data) {
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this.data = data;
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}
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}

‎appengine-java8/pubsub/src/main/java/com/example/appengine/pubsub/MessageRepository.java

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/**
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* Copyright 2017 Google Inc.
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*
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* <p>Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of the License at
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*
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* <p>http://www.apache.org/licenses/LICENSE-2.0
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*
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* <p>Unless required by applicable law or agreed to in writing, software distributed under the
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* License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
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* express or implied. 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.appengine.pubsub;
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import java.util.List;
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public interface MessageRepository {
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/** Save message to persistent storage. */
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void save(Message message);
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/**
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* Retrieve most recent stored messages.
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* @param limit number of messages
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* @return list of messages
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*/
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List<Message> retrieve(int limit);
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}

‎appengine-java8/pubsub/src/main/java/com/example/appengine/pubsub/MessageRepositoryImpl.java

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/**
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* Copyright 2017 Google Inc.
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*
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* <p>Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of the License at
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*
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* <p>http://www.apache.org/licenses/LICENSE-2.0
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*
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* <p>Unless required by applicable law or agreed to in writing, software distributed under the
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* License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
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* express or implied. 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.appengine.pubsub;
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import com.google.cloud.datastore.Datastore;
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import com.google.cloud.datastore.DatastoreOptions;
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import com.google.cloud.datastore.Entity;
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import com.google.cloud.datastore.Key;
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import com.google.cloud.datastore.KeyFactory;
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import com.google.cloud.datastore.Query;
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import com.google.cloud.datastore.QueryResults;
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import com.google.cloud.datastore.StructuredQuery;
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import java.util.ArrayList;
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import java.util.List;
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/** Storage for Message objects using Cloud Datastore. */
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public class MessageRepositoryImpl implements MessageRepository {
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private static MessageRepositoryImpl instance;
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private String messagesKind = "messages";
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private KeyFactory keyFactory = getDatastoreInstance().newKeyFactory().setKind(messagesKind);
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@Override
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public void save(Message message) {
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// Save message to "messages"
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Datastore datastore = getDatastoreInstance();
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Key key = datastore.allocateId(keyFactory.newKey());
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Entity.Builder messageEntityBuilder = Entity.newBuilder(key)
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.set("messageId", message.getMessageId());
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if (message.getData() != null) {
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messageEntityBuilder = messageEntityBuilder.set("data", message.getData());
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}
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if (message.getPublishTime() != null) {
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messageEntityBuilder = messageEntityBuilder.set("publishTime", message.getPublishTime());
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}
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datastore.put(messageEntityBuilder.build());
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}
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@Override
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public List<Message> retrieve(int limit) {
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// Get Message saved in Datastore
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Datastore datastore = getDatastoreInstance();
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Query<Entity> query =
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Query.newEntityQueryBuilder()
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.setKind(messagesKind)
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.setLimit(limit)
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.addOrderBy(StructuredQuery.OrderBy.desc("publishTime"))
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.build();
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QueryResults<Entity> results = datastore.run(query);
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List<Message> messages = new ArrayList<>();
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while (results.hasNext()) {
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Entity entity = results.next();
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Message message = new Message(entity.getString("messageId"));
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String data = entity.getString("data");
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if (data != null) {
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message.setData(data);
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}
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String publishTime = entity.getString("publishTime");
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if (publishTime != null) {
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message.setPublishTime(publishTime);
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}
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messages.add(message);
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}
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return messages;
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}
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private Datastore getDatastoreInstance() {
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return DatastoreOptions.getDefaultInstance().getService();
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}
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private MessageRepositoryImpl() {
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}
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// retrieve a singleton instance
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public static synchronized MessageRepositoryImpl getInstance() {
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if (instance == null) {
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instance = new MessageRepositoryImpl();
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}
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return instance;
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}
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}

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