Implementing Real-Time Features

@Configuration @EnableWebSocketMessageBroker
public class WsConfig implements WebSocketMessageBrokerConfigurer {
    public void registerStompEndpoints(StompEndpointRegistry r) {
        r.addEndpoint("/ws").setAllowedOriginPatterns("https://app.acme.com");
    }
    public void configureMessageBroker(MessageBrokerRegistry b) {
        b.enableSimpleBroker("/topic","/queue");
        b.setApplicationDestinationPrefixes("/app");
    }
}
@Controller class ChatController {
    @MessageMapping("/chat") @SendTo("/topic/chat")
    public ChatMessage onMessage(ChatMessage msg) { return msg; }
}

@GetMapping(value = "/orders/{id}/stream", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
public SseEmitter stream(@PathVariable UUID id) {
    var emitter = new SseEmitter(0L);
    eventBus.subscribe(id, event -> {
        try { emitter.send(SseEmitter.event().name("update").data(event)); }
        catch (IOException ex) { emitter.completeWithError(ex); }
    });
    return emitter;
}

// Publisher
redis.opsForValue().getOperations()
   .convertAndSend("chat:room:42", message);

// Subscriber
@Bean RedisMessageListenerContainer container(RedisConnectionFactory cf) {
    var c = new RedisMessageListenerContainer();
    c.setConnectionFactory(cf);
    c.addMessageListener((msg, pattern) -> broker.convertAndSend("/topic/chat/42", msg.getBody()),
        new PatternTopic("chat:room:*"));
    return c;
}