10000 Web Socket Sample - JSR-356 (#1280) · Vali5681/java-docs-samples@4d06536 · GitHub
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Web Socket Sample - JSR-356 (GoogleCloudPlatform#1280)
* copy over sample * update maven dependency * Update parent dependency
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‎appengine-java8/websocket-jsr356/README.md

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# App Engine Flexible Environment - Web Socket Example
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This sample demonstrates how to use [Websockets](https://tools.ietf.org/html/rfc6455) on [Google App Engine Flexible Environment](https://cloud.google.com/appengine/docs/flexible/java/) using Java.
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The sample uses the [JSR-356](https://www.jcp.org/en/jsr/detail?id=356) Java API for the Websocket [client](https://mvnrepository.com/artifact/org.eclipse.jetty.websocket/javax-websocket-client-impl).
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## Sample application workflow
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1. The sample application creates a server socket using the endpoint `/echo`.
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1. The homepage (`/`) provides a form to submit a text message to the server socket. This creates a client-side socket
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and sends the message to the server.
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1. The server on receiving the message, echoes the message back to the client.
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1. The message received by the client is stored in an in-memory cache and is viewable on the homepage.
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The sample also provides a Javascript [client](src/main/webapp/js_client.jsp)(`/js_client.jsp`) that you can use to test against the Websocket server.
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## Setup
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- [Install](https://cloud.google.com/sdk/) and initialize GCloud SDK. This will
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```
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gcloud init
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```
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- If this is your first time creating an app engine application
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```
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gcloud appengine create
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```
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## Local testing
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Run using the [Jetty Maven plugin](http://www.eclipse.org/jetty/documentation/9.4.x/jetty-maven-plugin.html).
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```
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mvn jetty:run
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```
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You can then direct your browser to `http://localhost:8080/`
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To test the Javascript client, access `http://localhost:8080/js_client.jsp`
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## App Engine Flex Deployment
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#### `app.yaml` Configuration
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App Engine Flex deployment configuration is provided in [app.yaml](src/main/appengine/app.yaml).
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Set the environment variable `JETTY_MODULES_ENABLE:websocket` to enable the Jetty websocket module on the Jetty server.
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Manual scaling is set to a single instance as we are using an in-memory cache of messages for this sample application.
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For more details on configuring your `app.yaml`, please refer to [this resource](https://cloud.google.com/appengine/docs/flexible/nodejs/configuring-your-app-with-app-yaml).
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#### Deploy
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The sample application is packaged as a war, and hence will be automatically run using the [Java 8/Jetty 9 with Servlet 3.1 Runtime](https://cloud.google.com/appengine/docs/flexible/java/dev-jetty9).
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```
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mvn appengine:deploy
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```
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You can then direct your browser to `https://YOUR_PROJECT_ID.appspot.com/`
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To test the Javascript client, access `https://YOUR_PROJECT_ID.appspot.com/js_client.jsp`

‎appengine-java8/websocket-jsr356/pom.xml

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<!--
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Copyright 2018 Google LLC
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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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<version>1.0-SNAPSHOT</version>
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<groupId>com.example.flexible</groupId>
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<artifactId>appengine-websocket-jsr356</artifactId>
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<packaging>war</packaging>
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<!--
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The parent pom defines common style checks and testing strategies for our samples.
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Removing or replacing it should not effect the execution of the samples in anyway.
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-->
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<parent>
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<groupId>com.google.cloud.samples</groupId>
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<artifactId>shared-configuration</artifactId>
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<version>1.0.10</version>
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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>1.3.2</appengine.maven.plugin>
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<jetty.version>9.4.4.v20170414</jetty.version>
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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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<!--Jetty JSR-356 Websocket client side dependency-->
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<dep 10000 endency>
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<groupId>org.eclipse.jetty.websocket</groupId>
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<artifactId>javax-websocket-client-impl</artifactId>
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<version>${jetty.version}</version>
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</dependency>
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<!--Optional dependency for SettableFuture, see com.example.flexible.websocket.jsr356.ServerSocket -->
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<dependency>
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<groupId>com.google.guava</groupId>
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<artifactId>guava</artifactId>
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<version>20.0</version>
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</dependency>
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</dependencies>
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<build>
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<!-- for hot reload of the web application -->
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<outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/classes
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</outputDirectory>
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<plugins>
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<!-- for deployment of web application -->
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<plugin>
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<groupId>com.google.cloud.tools</groupId>
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<artifactId>appengine-maven-plugin</artifactId>
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<version>${appengine.maven.plugin}</version>
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<configuration>
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</configuration>
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</plugin>
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<!-- for local testing of web application -->
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<plugin>
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<groupId>org.eclipse.jetty</groupId>
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<artifactId>jetty-maven-plugin</artifactId>
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<version>${jetty.version}</version>
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</plugin>
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</plugins>
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</build>
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</project>

‎appengine-java8/websocket-jsr356/src/main/appengine/app.yaml

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# Copyright 2018 Google LLC
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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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runtime: java
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env: flex
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manual_scaling:
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instances: 1
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handlers:
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- url: /.*
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script: this field is required, but ignored
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env_variables:
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JETTY_MODULES_ENABLE: websocket
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# For applications which can take advantage of session affinity
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# (where the load balancer will attempt to route multiple connections from
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# the same user to the same App Engine instance), uncomment the folowing:
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# network:
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# session_affinity: true

‎appengine-java8/websocket-jsr356/src/main/java/com/example/flexible/websocket/jsr356/ClientSocket.java

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/*
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* Copyright 2018 Google LLC
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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.flexible.websocket.jsr356;
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import com.google.common.util.concurrent.SettableFuture;
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import java.net.URI;
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import java.util.Collection;
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import java.util.Collections;
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import java.util.concurrent.ConcurrentLinkedDeque;
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import java.util.concurrent.ExecutionException;
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import java.util.logging.Logger;
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import javax.websocket.ClientEndpoint;
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import javax.websocket.CloseReason;
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import javax.websocket.ContainerProvider;
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import javax.websocket.OnClose;
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import javax.websocket.OnError;
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import javax.websocket.OnMessage;
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import javax.websocket.OnOpen;
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import javax.websocket.Session;
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import javax.websocket.WebSocketContainer;
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/**
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* Web socket client example using JSR-356 Java WebSocket API. Sends a message to the server, and
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* stores the echoed messages received from the server.
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*/
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@ClientEndpoint
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public class ClientSocket {
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private static final Logger logger = Logger.getLogger(ClientSocket.class.getName());
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// stores the messages in-memory.
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// Note : this is currently an in-memory store for demonstration,
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// not recommended for production use-cases.
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private static Collection<String> messages = new ConcurrentLinkedDeque<>();
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private SettableFuture<Boolean> future = SettableFuture.create();
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private Session session;
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ClientSocket(URI endpointUri) {
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try {
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WebSocketContainer container = ContainerProvider.getWebSocketContainer();
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session = container.connectToServer(this, endpointUri);
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} catch (Exception e) {
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throw new RuntimeException(e);
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}
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}
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@OnOpen
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public void onOpen(Session session) {
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future.set(true);
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}
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/**
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* Handles message received from the server.
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* @param message server message in String format
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* @param session current session
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*/
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@OnMessage
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public void onMessage(String message, Session session) {
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logger.fine("Received message from server : " + message);
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messages.add(message);
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}
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boolean waitOnOpen() throws InterruptedException, ExecutionException {
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// wait on handling onOpen
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boolean opened = future.get();
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logger.fine("Connected to server");
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return opened;
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}
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@OnClose
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public void onClose(CloseReason reason, Session session) {
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logger.fine("Closing Web Socket: " + reason.getReasonPhrase());
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}
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void sendMessage(String str) {
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try {
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// Send a message to the server
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logger.fine("Sending message : " + str);
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session.getAsyncRemote().sendText(str);
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} catch (Exception e) {
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logger.severe("Error sending message : " + e.getMessage());
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}
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}
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// Retrieve all received messages.
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public static Collection<String> getReceivedMessages() {
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return Collections.unmodifiableCollection(messages);
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}
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@OnError
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public void logErrors(Throwable t) {
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logger.severe(t.getMessage());
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}
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}

‎appengine-java8/websocket-jsr356/src/main/java/com/example/flexible/websocket/jsr356/SendServlet.java

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/*
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* Copyright 2018 Google LLC
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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.flexible.websocket.jsr356;
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import com.google.common.base.Preconditions;
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import java.io.IOException;
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import java.net.URI;
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import java.net.URISyntaxException;
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import java.util.logging.Logger;
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import javax.servlet.annotation.WebServlet;
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import javax.servlet.http.HttpServlet;
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import javax.servlet.http.HttpServletRequest;
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import javax.servlet.http.HttpServletResponse;
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import org.eclipse.jetty.http.HttpStatus;
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@WebServlet("/send")
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/** Servlet that converts the message sent over POST to be over websocket. */
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public class SendServlet extends HttpServlet {
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private Logger logger = Logger.getLogger(SendServlet.class.getName());
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private final String webSocketAddress = ServerSocket.getWebSocketAddress();
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private ClientSocket clientSocket;
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private void initializeWebSocket() throws Exception {
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clientSocket = new ClientSocket(new URI(webSocketAddress));
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clientSocket.waitOnOpen();
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logger.info("REST service: open websocket client at " + webSocketAddress);
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}
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private void sendMessageOverWebSocket(String message) throws Exception {
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if (clientSocket == null) {
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try {
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initializeWebSocket();
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} catch (URISyntaxException e) {
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e.printStackTrace();
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}
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}
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clientSocket.sendMessage(message);
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}
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@Override
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public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
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String message = request.getParameter("message");
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Preconditions.checkNotNull(message);
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try {
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sendMessageOverWebSocket(message);
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response.sendRedirect("/");
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} catch (Exception e) {
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e.printStackTrace(response.getWriter());
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response.setStatus(HttpStatus.INTERNAL_SERVER_ERROR_500);
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}
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}
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}

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