GraphQL APIs with Spring Boot · Lesson

Integrating WebSockets with Spring

Configure WebSocket support in your Spring Boot application to enable persistent client-server connections for subscriptions.

Integrating WebSockets with Spring is a free GraphQL APIs with Spring Boot lesson on CoddyKit — lesson 3 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the GraphQL APIs with Spring Boot learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

WebSockets for Real-time Data

Welcome! In this lesson, we'll integrate WebSockets with Spring Boot. This is crucial for enabling real-time features like GraphQL Subscriptions.

WebSockets provide a persistent, two-way communication channel between a client and a server over a single, long-lived TCP connection.

Why WebSockets for Subscriptions?

Unlike traditional HTTP requests (which are short-lived), GraphQL Subscriptions require a continuous connection to push data updates to clients as they happen.

WebSockets are the perfect fit because they maintain an open connection, allowing the server to send data to the client at any time without a new request.

Adding the Dependency

First, we need to add the Spring Boot WebSocket starter dependency to our project. This brings in all the necessary libraries to enable WebSocket support.

For Gradle, add this to your build.gradle:

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-websocket'
}

Enabling WebSocket Message Broker

In Spring, we use annotations to enable specific functionalities. For WebSockets with a message broker, we use @EnableWebSocketMessageBroker.

This annotation enables a STOMP over WebSocket message broker, which is a powerful way to handle messaging.

Configuring WebSocket Endpoints

We need a configuration class that extends WebSocketMessageBrokerConfigurer. This class allows us to customize our WebSocket setup.

The registerStompEndpoints() method is used to define the URL endpoint clients will connect to for WebSocket communication.

Adding SockJS Fallback

When registering an endpoint, we often add .withSockJS(). SockJS is a JavaScript library that provides a WebSocket-like API.

It offers fallback options (like HTTP streaming or long polling) for browsers that don't fully support WebSockets or in environments with proxies that interfere.

Configuring the Message Broker

The configureMessageBroker() method sets up the message broker itself. This defines how messages are routed between clients and the application.

enableSimpleBroker("/topic"): Enables an in-memory message broker for destinations prefixed with /topic. Clients subscribe to these topics.
setApplicationDestinationPrefixes("/app"): Defines prefixes for messages destined for methods annotated with @MessageMapping in our application.

Complete WebSocket Configuration

Here's a minimal Spring Boot application demonstrating the WebSocket configuration. Try running it to see Spring initialize the WebSocket server!

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Configuration;
import org.springframework.messaging.simp.config.MessageBrokerRegistry;
import org.springframework.web.socket.config.annotation.EnableWebSocketMessageBroker;
import org.springframework.web.socket.config.annotation.StompEndpointRegistry;
import org.springframework.web.socket.config.annotation.WebSocketMessageBrokerConfigurer;

@SpringBootApplication
public class Main {
  public static void main(String[] args) {
    SpringApplication.run(Main.class, args);
    System.out.println("WebSocket server ready on port 8080!");
    System.out.println("Connect at ws://localhost:8080/ws-connect");
  }

  @Configuration
  @EnableWebSocketMessageBroker
  static class WebSocketConfig implements WebSocketMessageBrokerConfigurer {

      @Override
      public void registerStompEndpoints(StompEndpointRegistry registry) {
          registry.addEndpoint("/ws-connect")
                  .withSockJS(); 
      }

      @Override
      public void configureMessageBroker(MessageBrokerRegistry config) {
          config.enableSimpleBroker("/topic");
          config.setApplicationDestinationPrefixes("/app");
      }
  }
}

Bridging to GraphQL Subscriptions

With this WebSocket infrastructure, our GraphQL subscription resolvers (from the previous lesson) can now publish events.

When a resolver publishes an event, Spring's message broker ensures that all clients subscribed to the relevant /topic are immediately notified via their open WebSocket connection.

Quick Check: WebSocket Config

Consider the following line from our WebSocket configuration:

config.enableSimpleBroker("/topic");

What is the primary purpose of the /topic prefix in this context?

Recap: WebSockets in Spring

Great job! You've learned how to integrate WebSockets with Spring Boot to provide a robust real-time communication layer.

We added the WebSocket starter dependency.
We used @EnableWebSocketMessageBroker and WebSocketMessageBrokerConfigurer.
We configured STOMP endpoints (e.g., /ws-connect with SockJS).
We set up a message broker with prefixes like /topic for subscriptions and /app for app-specific messages.

This setup is the foundation for delivering real-time GraphQL Subscriptions!

Frequently asked questions

Is the “Integrating WebSockets with Spring” lesson free?

Yes — the full text of “Integrating WebSockets with Spring” is free to read here on the web, and the GraphQL APIs with Spring Boot course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the GraphQL APIs with Spring Boot course, upgrade to CoddyKit PRO.

What will I learn in “Integrating WebSockets with Spring”?

Configure WebSocket support in your Spring Boot application to enable persistent client-server connections for subscriptions. You practise GraphQL APIs with Spring Boot with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start GraphQL APIs with Spring Boot?

No prior experience is required. GraphQL APIs with Spring Boot on CoddyKit is structured for beginners through advanced learners; this is — lesson 3 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Integrating WebSockets with Spring” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this GraphQL APIs with Spring Boot lesson?

Yes. Every GraphQL APIs with Spring Boot lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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