How do you implement Spring Boot with WebSockets?

Table of Contents

• Introduction
• Setting Up WebSockets in Spring Boot
  • 1. Add WebSocket Dependencies to Your Spring Boot Application
    • Maven Dependency
    • Gradle Dependency
  • 2. Configure WebSocket in Spring Boot
    • Example: WebSocket Configuration
  • 3. Create a WebSocket Controller
    • Example: WebSocket Controller
  • 4. Set Up a WebSocket Client (HTML + JavaScript)
    • Example: WebSocket Client
  • 5. Running the Application
  • 6. Handling Messages in the Controller
• Conclusion

Introduction

WebSockets provide full-duplex communication channels over a single, long-lived connection between a client and server. They are perfect for real-time web applications, such as live notifications, chat applications, and stock tickers. Spring Boot, with its extensive support for WebSockets, offers an easy way to implement WebSocket-based messaging and communication in your applications. This guide explains how to set up WebSocket communication in a Spring Boot application using STOMP (Simple Text Oriented Messaging Protocol) over WebSocket and SockJS as a fallback for clients that don't support WebSocket natively.

Setting Up WebSockets in Spring Boot

1. Add WebSocket Dependencies to Your Spring Boot Application

To use WebSockets in Spring Boot, you need to include the necessary dependencies in your pom.xml file (for Maven) or build.gradle (for Gradle).

Maven Dependency

Gradle Dependency

These dependencies provide everything you need to get WebSocket support in your Spring Boot application, including WebSocket handling, messaging, and STOMP protocol support.

2. Configure WebSocket in Spring Boot

To configure WebSockets, you'll need to create a configuration class that enables WebSocket support and configures the messaging protocols (STOMP and SockJS).

Example: WebSocket Configuration

In this configuration:

• @EnableWebSocketMessageBroker: Enables WebSocket messaging in your application.
• configureMessageBroker: Configures a simple message broker for STOMP communication and defines the prefix for the application destinations.
• registerStompEndpoints: Registers the WebSocket endpoint that clients can connect to. withSockJS() is used to provide fallback options for clients that don’t support WebSocket.

3. Create a WebSocket Controller

Now that the WebSocket is configured, you need to create a controller to handle the WebSocket messages and send data to connected clients.

Example: WebSocket Controller

In this controller:

• The @MessageMapping("/hello") annotation maps incoming messages sent to /app/hello to the greeting() method.
• The SimpMessagingTemplate is used to send a message to all clients subscribed to /topic/greetings.

4. Set Up a WebSocket Client (HTML + JavaScript)

The client needs to connect to the WebSocket endpoint (/ws), send messages to the server, and subscribe to topics to receive messages. Here's an example of a simple client using JavaScript and STOMP.

Example: WebSocket Client

In this client:

• SockJS provides a fallback for WebSocket, ensuring compatibility with clients that don’t support native WebSocket.
• STOMP is used to send and receive messages. The client subscribes to the /topic/greetings topic to receive messages and sends data to the /app/hello endpoint.

5. Running the Application

To test the WebSocket functionality, run your Spring Boot application. The WebSocket server will be accessible at the /ws endpoint, and the client can connect to it through the provided HTML page. Once a user enters their name and clicks "Send," the server will respond with a greeting that is displayed on the page.

6. Handling Messages in the Controller

The WebSocket controller can be expanded to handle various messaging operations, such as broadcasting, private messaging, or handling multiple topics. You can create more @MessageMapping methods to handle different endpoints or use @SendTo to send messages to multiple destinations.

Conclusion

Integrating WebSockets in a Spring Boot application is straightforward with the use of STOMP and SockJS, which provide a reliable communication channel for real-time messaging. By following the steps outlined in this guide, you can quickly implement WebSocket communication to build interactive applications such as chat services, notifications, and live data feeds. The combination of Spring Boot and WebSockets provides a robust and scalable solution for handling real-time messaging in modern web applications.