I'm using Spring 5: how do I detect SUBSCRIBE messages from a Stomp client?
Per my understanding, @SubscribeMapping should make my controller method be called whenever a client subscribes to a topic, but that's not happening.
Here's my server controller:
@Controller
public class MessageController {
// ...
@MessageMapping("/chat/{mId}")
@SendTo("/topic/messages")
public OutputMessage send(Message message, @DestinationVariable("mId") String mid, MessageHeaders headers, MessageHeaderAccessor accessor) throws Exception {
// ...
}
@SuppressWarnings("unused")
@SubscribeMapping({ "/", "/chat", "/topic/messages", "/messages", "/*" })
public void listen(Message message, MessageHeaders headers, MessageHeaderAccessor accessor) throws Exception {
int i = 0;
System.out.println("subscribed");
}
}
Server configuration:
@Configuration
@ComponentScan(basePackages= { "websockets" })
@EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {
@Override
public void configureMessageBroker(MessageBrokerRegistry config) {
config.enableSimpleBroker("/topic");
config.setApplicationDestinationPrefixes("/app");
}
@Override
public void registerStompEndpoints(StompEndpointRegistry registry) {
registry.addEndpoint("/chat");
registry.addEndpoint("/chat").withSockJS();
}
@Override
public void configureWebSocketTransport(WebSocketTransportRegistration registry) {
WebSocketMessageBrokerConfigurer.super.configureWebSocketTransport(registry);
}
}
And the javascript client:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<title>Chat WebSocket</title>
<script src="sockjs.js"></script>
<script src="stomp.js"></script>
<script type="text/javascript">
// ...
function connect() {
var sock = new SockJS('/<webapp-context>/chat');
stompClient = Stomp.over(sock);
stompClient.connect({}, function(frame) {
setConnected(true);
console.log('Connected: ' + frame);
stompClient.subscribe('/topic/messages', function(messageOutput) {
showMessageOutput(JSON.parse(messageOutput.body));
});
stompClient.subscribe('/topic/messages/13', function(messageOutput) {
showMessageOutput(JSON.parse(messageOutput.body));
});
});
}
// ...
</script>
</head>
<body onload="/*disconnect()*/">
<!-- ... -->
</body>
</html>
The code has been adapted from Intro to WebSockets with Spring.
As indicated in this answer and in the docs, I can just use an interceptor, but how does @SubscribeMapping work then?
You need to register "topic" also as application destination topic config.setApplicationDestinationPrefixes({"/app", "/topic"});.
Otherwise Spring won't forward the subscribe message to the application and just forward it to the message broker channel.