How do you create a WebSocket configuration in Spring Boot?

Table of Contents

• Introduction
• Steps to Create a WebSocket Configuration in Spring Boot
  • 1. Add Dependencies to pom.xml (Maven)
  • 2. Create WebSocket Configuration Class
    • Example: WebSocket Configuration
  • 3. Create a WebSocket Controller
    • Example: WebSocket Controller
  • 4. Create a WebSocket Client (HTML + JavaScript)
    • Example: WebSocket Client
  • 5. Running the Application
• Conclusion

Introduction

WebSockets provide a full-duplex communication channel between a client and a server, making them ideal for real-time applications like messaging systems, live updates, and notifications. In Spring Boot, creating a WebSocket configuration is straightforward and leverages Spring's messaging module. By setting up WebSocket endpoints and message brokers, developers can handle real-time communication with minimal setup. This guide will walk you through creating WebSocket configuration in a Spring Boot application.

Steps to Create a WebSocket Configuration in Spring Boot

1. Add Dependencies to pom.xml (Maven)

To use WebSockets in Spring Boot, you need to include the necessary dependencies in your pom.xml. The spring-boot-starter-websocket dependency enables WebSocket support.

If you are using Gradle, the equivalent dependencies would be:

These dependencies include the necessary libraries for WebSocket communication and messaging in Spring Boot.

2. Create WebSocket Configuration Class

To configure WebSocket support in Spring Boot, create a Java configuration class that enables WebSocket handling and sets up the messaging system.

Example: WebSocket Configuration

In this configuration:

• @EnableWebSocketMessageBroker: This annotation enables WebSocket messaging support in the application and allows message handling with STOMP.
• configureMessageBroker: This method configures a simple in-memory message broker to send messages to clients. It also sets up prefixes for application destinations.
  • /topic: This prefix is used for destinations that the client subscribes to, such as live updates.
  • /app: This prefix is for destinations where the client sends messages (e.g., for requesting updates or sending commands).
• registerStompEndpoints: This method registers the WebSocket endpoint /ws for clients to connect to. Using .withSockJS() ensures fallback support for browsers that don’t natively support WebSockets (like older versions of Internet Explorer).

3. Create a WebSocket Controller

After setting up the WebSocket configuration, create a controller that handles incoming messages and sends responses to clients.

Example: WebSocket Controller

In this example:

• @MessageMapping("/hello")This annotation maps messages sent to /app/hello to the greeting() method.
• SimpMessagingTemplate: This class is used to send messages to destinations like /topic/greetings, which the clients subscribe to.

4. Create a WebSocket Client (HTML + JavaScript)

To test your WebSocket setup, create a simple client using HTML and JavaScript. The client will connect to the WebSocket endpoint, send a message to the server, and subscribe to a topic to receive messages.

Example: WebSocket Client

In this client:

• SockJS provides WebSocket support with fallback for clients that do not support WebSockets natively.
• STOMP handles message sending and receiving. The client subscribes to /topic/greetings and sends a message to the /app/hello endpoint when the button is clicked.

5. Running the Application

1. Start the Spring Boot application: Run the Spring Boot application by executing mvn spring-boot:run (for Maven) or gradle bootRun (for Gradle).
2. Open the HTML file in a browser: Open the client-side HTML file in a web browser to connect to the WebSocket server.
3. Test the WebSocket connection: Enter a name in the input field and click "Send". You should see a greeting message displayed in real-time as the server responds.

Conclusion

Creating a WebSocket configuration in Spring Boot is relatively simple and provides powerful features for real-time communication in your applications. By setting up a WebSocket endpoint, defining message brokers, and using STOMP over WebSocket, you can easily implement live, bidirectional communication. Whether you're building a chat app, live notifications, or data feeds, Spring Boot’s WebSocket support helps you manage real-time communication efficiently.