versión:

Using WebSockets

This guide explains how your Quarkus application can utilize web sockets to create interactive web applications. Because it’s the canonical web socket application, we are going to create a simple chat application.

Requisitos previos

To complete this guide, you need:

Roughly 15 minutes
An IDE
JDK 17+ installed with JAVA_HOME configured appropriately
Apache Maven 3.9.6
Optionally the Quarkus CLI if you want to use it
Optionally Mandrel or GraalVM installed and configured appropriately if you want to build a native executable (or Docker if you use a native container build)

Arquitectura

In this guide, we create a straightforward chat application using web sockets to receive and send messages to the other connected users.

Architecture

Solución

We recommend that you follow the instructions in the next sections and create the application step by step. However, you can skip right to the completed example.

Clone el repositorio Git: git clone https://github.com/quarkusio/quarkus-quickstarts.git o descargue un archivo.

The solution is located in the websockets-quickstart directory.

Creación del proyecto Maven

En primer lugar, necesitamos un nuevo proyecto. Cree un nuevo proyecto con el siguiente comando:

CLI

quarkus create app org.acme:websockets-quickstart \
    --extension='websockets' \
    --no-code
cd websockets-quickstart

To create a Gradle project, add the --gradle or --gradle-kotlin-dsl option.

For more information about how to install and use the Quarkus CLI, see the Quarkus CLI guide.

Maven

mvn io.quarkus.platform:quarkus-maven-plugin:3.9.3:create \
    -DprojectGroupId=org.acme \
    -DprojectArtifactId=websockets-quickstart \
    -Dextensions='websockets' \
    -DnoCode
cd websockets-quickstart

To create a Gradle project, add the -DbuildTool=gradle or -DbuildTool=gradle-kotlin-dsl option.

For Windows users:

If using cmd, (don’t use backward slash \ and put everything on the same line)
If using Powershell, wrap -D parameters in double quotes e.g. "-DprojectArtifactId=websockets-quickstart"

This command generates the project (without any classes) and imports the websockets extension.

If you already have your Quarkus project configured, you can add the websockets extension to your project by running the following command in your project base directory:

CLI

quarkus extension add websockets

Maven

./mvnw quarkus:add-extension -Dextensions='websockets'

Gradle

./gradlew addExtension --extensions='websockets'

Esto añadirá lo siguiente a su archivo de construcción:

pom.xml

<dependency>
    <groupId>io.quarkus</groupId>
    <artifactId>quarkus-websockets</artifactId>
</dependency>

build.gradle

implementation("io.quarkus:quarkus-websockets")

If you only want to use the WebSocket client you should include quarkus-websockets-client instead.

Handling web sockets

Our application contains a single class that handles the web sockets. Create the org.acme.websockets.ChatSocket class in the src/main/java directory. Copy the following content into the created file:

package org.acme.websockets;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import jakarta.enterprise.context.ApplicationScoped;
import jakarta.websocket.OnClose;
import jakarta.websocket.OnError;
import jakarta.websocket.OnMessage;
import jakarta.websocket.OnOpen;
import jakarta.websocket.server.PathParam;
import jakarta.websocket.server.ServerEndpoint;
import jakarta.websocket.Session;

@ServerEndpoint("/chat/{username}")         (1)
@ApplicationScoped
public class ChatSocket {

    Map<String, Session> sessions = new ConcurrentHashMap<>(); (2)

    @OnOpen
    public void onOpen(Session session, @PathParam("username") String username) {
        broadcast("User " + username + " joined");
        sessions.put(username, session);
    }

    @OnClose
    public void onClose(Session session, @PathParam("username") String username) {
        sessions.remove(username);
        broadcast("User " + username + " left");
    }

    @OnError
    public void onError(Session session, @PathParam("username") String username, Throwable throwable) {
        sessions.remove(username);
        broadcast("User " + username + " left on error: " + throwable);
    }

    @OnMessage
    public void onMessage(String message, @PathParam("username") String username) {
        broadcast(">> " + username + ": " + message);
    }

    private void broadcast(String message) {
        sessions.values().forEach(s -> {
            s.getAsyncRemote().sendObject(message, result ->  {
                if (result.getException() != null) {
                    System.out.println("Unable to send message: " + result.getException());
                }
            });
        });
    }

}

1	Configures the web socket URL
2	Stores the currently opened web sockets

A slick web frontend

All chat applications need a nice UI, well, this one may not be that nice, but does the work. Quarkus automatically serves static resources contained in the META-INF/resources directory. Create the src/main/resources/META-INF/resources directory and copy this index.html file in it.

Run the application

Now, let’s see our application in action. Run it with:

CLI

quarkus dev

Maven

./mvnw quarkus:dev

Gradle

./gradlew --console=plain quarkusDev

Then open your 2 browser windows to http://localhost:8080/:

Enter a name in the top text area (use 2 different names).
Click on connect
Send and receive messages

Application

As usual, the application can be packaged using:

CLI

quarkus build

Maven

./mvnw install

Gradle

./gradlew build

And executed using java -jar target/quarkus-app/quarkus-run.jar.

You can also build the native executable using:

CLI

quarkus build --native

Maven

./mvnw install -Dnative

Gradle

./gradlew build -Dquarkus.package.type=native

You can also test your web socket applications using the approach detailed here.

WebSocket Clients

Quarkus also contains a WebSocket client. You can call ContainerProvider.getWebSocketContainer().connectToServer to create a websocket connection. By default, the quarkus-websockets artifact includes both client and server support. However, if you only want the client you can include quarkus-websockets-client instead.

When you connect to the server you can either pass in the Class of the annotated client endpoint you want to use, or an instance of jakarta.websocket.Endpoint. If you are using the annotated endpoint then you can use the exact same annotations as you can on the server, except it must be annotated with @ClientEndpoint instead of @ServerEndpoint.

The example below shows the client being used to test the chat endpoint above.

package org.acme.websockets;

import java.net.URI;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.TimeUnit;

import jakarta.websocket.ClientEndpoint;
import jakarta.websocket.ContainerProvider;
import jakarta.websocket.OnMessage;
import jakarta.websocket.OnOpen;
import jakarta.websocket.Session;

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;

import io.quarkus.test.common.http.TestHTTPResource;
import io.quarkus.test.junit.QuarkusTest;

@QuarkusTest
public class ChatTest {

    private static final LinkedBlockingDeque<String> MESSAGES = new LinkedBlockingDeque<>();

    @TestHTTPResource("/chat/stu")
    URI uri;

    @Test
    public void testWebsocketChat() throws Exception {
        try (Session session = ContainerProvider.getWebSocketContainer().connectToServer(Client.class, uri)) {
            Assertions.assertEquals("CONNECT", MESSAGES.poll(10, TimeUnit.SECONDS));
            Assertions.assertEquals("User stu joined", MESSAGES.poll(10, TimeUnit.SECONDS));
            session.getAsyncRemote().sendText("hello world");
            Assertions.assertEquals(">> stu: hello world", MESSAGES.poll(10, TimeUnit.SECONDS));
        }
    }

    @ClientEndpoint
    public static class Client {

        @OnOpen
        public void open(Session session) {
            MESSAGES.add("CONNECT");
            // Send a message to indicate that we are ready,
            // as the message handler may not be registered immediately after this callback.
            session.getAsyncRemote().sendText("_ready_");
        }

        @OnMessage
        void message(String msg) {
            MESSAGES.add(msg);
        }

    }

}

More WebSocket Information

The Quarkus WebSocket implementation is an implementation of Jakarta Websockets.

Requisitos previos
Arquitectura
Solución
Creación del proyecto Maven
Handling web sockets
A slick web frontend
Run the application
WebSocket Clients
More WebSocket Information