Developing Java applications with GlassFish and Java API for WebSocket (JSR 356)

17 Sep 2023

The Java API for WebSocket, also known as JSR 356, is a powerful API that allows developers to create real-time, bidirectional communication between clients and servers over a single, long-lived connection. In this blog post, we will explore how to develop Java applications using GlassFish, a leading Java EE application server, along with the JSR 356 API.

Getting Started

Before we dive into the details, let’s make sure you have all the necessary tools and dependencies in place to develop Java applications with GlassFish and JSR 356.

Prerequisites

Java Development Kit (JDK) installed on your system (version 8 or higher)
GlassFish application server installed (version 5 or higher)
IDE of your choice (Eclipse, IntelliJ, etc.) with Java EE support

Setting Up GlassFish

To get started, follow these steps to set up GlassFish on your machine:

Download the latest version of GlassFish from the official website.
Unzip the downloaded file to a directory of your choice.
Open a terminal or command prompt, navigate to the bin directory inside the GlassFish installation folder, and run the following command to start the GlassFish server:

./asadmin start-domain

You should see output indicating the successful startup of the GlassFish server.

Creating a WebSocket Application

Now that we have GlassFish up and running, let’s create a simple WebSocket application using the JSR 356 API.

Step 1: Create a Maven Project

Open your IDE and create a new Maven project. You can choose the appropriate archetype for your project type (web, enterprise, etc.) and fill in the required details.

Step 2: Add Dependencies

Next, add the following dependencies to your project’s Maven pom.xml file:

<dependency>
    <groupId>javax.websocket</groupId>
    <artifactId>javax.websocket-api</artifactId>
    <version>1.1</version>
</dependency>

<dependency>
    <groupId>org.glassfish.tyrus</groupId>
    <artifactId>tyrus-server</artifactId>
    <version>1.14</version>
</dependency>

These dependencies include the JSR 356 API and the GlassFish implementation of the WebSocket server.

Step 3: Create a WebSocket Endpoint

Now, let’s create a WebSocket endpoint that handles incoming messages and broadcasts them to connected clients. Create a new Java class in your project and annotate it with the @ServerEndpoint annotation, like this:

import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;

@ServerEndpoint("/websocket")
public class MyWebSocketEndpoint {

    @OnOpen
    public void onOpen(Session session) {
        // Handle new client connection
    }

    @OnMessage
    public void onMessage(String message, Session session) {
        // Handle incoming message
    }

    @OnClose
    public void onClose(Session session) {
        // Handle client disconnection
    }

    @OnError
    public void onError(Throwable error) {
        // Handle WebSocket error
    }
}

Step 4: Deploy and Test

Finally, let’s deploy and test our WebSocket application on GlassFish. Build your project using Maven and deploy the generated artifact to your GlassFish installation. Once deployed, you can access your WebSocket endpoint using the following URL:

ws://localhost:8080/your-app-context/websocket

Replace your-app-context with the context path of your application.

Conclusion

In this blog post, we learned how to develop Java applications using GlassFish and the Java API for WebSocket (JSR 356). We explored the necessary setup steps, creating a WebSocket endpoint, and deploying the application on GlassFish. This powerful combination allows you to build real-time, interactive web applications with ease.

#JavaDevelopment #WebSocketAPI