I actually write for Baeldung too and am currently writing a small article about how to add security to websockets in Spring! There are just a few steps you need to do to get this all working!
Backend-wise (since you said the UI was already done or being built, I'll just focus on the backend here), it really involves three parts: (1) the necessary POJO's, the controller, and the configuration.
Your POJO's will be very simple - here we just use Greeting and Message which specify a name and basic text data type (I'll skip over this here to save space but you can see it in the resource below).
Your controller will look like this:
@Controller
public class GreetingController {
@MessageMapping("/hello")
@SendTo("/topic/greetings")
public Greeting greeting(HelloMessage message) throws Exception {
Thread.sleep(1000); // simulated delay
return new Greeting("Hello, " + message.getName() + "!");
}
}
Take a look at the annotations - those are really what set this controller apart from say a normal REST controller.
And your configuration looks like this - again take a look at the annotations - particularly '@EnableWebSocketMessageBroker' - and the class 'AbstractWebSocketMessageBrokerConfigurer':
@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {
@Override
public void configureMessageBroker(MessageBrokerRegistry config) {
config.enableSimpleBroker("/topic");
config.setApplicationDestinationPrefixes("/app");
}
@Override
public void registerStompEndpoints(StompEndpointRegistry registry) {
registry.addEndpoint("/gs-guide-websocket").withSockJS();
}
}
A look at this great resource too: https://spring.io/guides/gs/messaging-stomp-websocket/
