get native header when a user connects

Question

I have clients connecting like this on a websocket

var socket = new SockJS(this.props.stomp);
var stompClient = Stomp.over(socket);
var channel = "/room."+this.props.room.uid
var app = this;
stompClient.connect({room: this.props.room.uid}, function(frame) {
....

and on my Java backend I'm trying to get this header following a tutorial:

public void onApplicationEvent(SessionConnectEvent event) {
    StompHeaderAccessor sha = StompHeaderAccessor.wrap(event.getMessage());

    String  room = sha.getNativeHeader("room").get(0);
    logger.debug("Connect event [sessionId: " + sha.getSessionId() +"; room: "+ room + " ]");
}

but the room is null at this point.
I debugged and found a very complex hierarchy: a MessageHeaderAccessor contains a map that contains a LinkedList that have a key called nativeHeaders that contains these native headers.
My question: is there a easy way to access this native header? so far, I only get things like

MessageHeaderAccessor accessor = NativeMessageHeaderAccessor.getAccessor(event.getMessage(), SimpMessageHeaderAccessor.class);
accessor.getMessageHeaders();
Object header = accessor.getHeader("simpConnectMessage");
GenericMessage<?> generic = (GenericMessage<?>) accessor.getHeader("simpConnectMessage");
System.out.println(generic.getHeaders().get("nativeHeaders"));

that I really found hard to understand and to use. Actually, the only thing I want is to track the current numbers of users connect to a channel and I think that implement a ApplicationListener is the way. I might be wrong here, so if anyone found something or implemented anything similar, I would like to know

score 3 · Answer 1 · answered Mar 22 '21 at 15:48

I did it in such way:

javascript snippet

function connect() {
    var socket = new SockJS('http://localhost:8081/ws/notification');
    stompClient = Stomp.over(socket);

    var header = {
        "user-id" : "bb2c9039-0ed3-4d6f-b078-db965286944d"
    }

    stompClient.connect(header, function (frame) {
        console.log('Connected: ' + frame);
        stompClient.subscribe('/user/ws/notification/message', function (greeting) {
            showGreeting(JSON.parse(greeting.body).name);
        });
    });
}

Java snippet

@EventListener
public void handleWebSocketConnectListener(SessionConnectedEvent event) {
    StompHeaderAccessor accessor = StompHeaderAccessor.wrap(event.getMessage());

    String sessionId = accessor.getMessageHeaders().get(SimpMessageHeaderAccessor.SESSION_ID_HEADER, String.class);
    String userId = getUserId(accessor);

    log.info("User( user-id: {} ) established new WebSocket session( session-id: {} ).", userId, sessionId);
    putSessionIdToMap(sessionId, userId);
}

private String getUserId(StompHeaderAccessor accessor) {
    GenericMessage<?> generic = (GenericMessage<?>) accessor.getHeader(SimpMessageHeaderAccessor.CONNECT_MESSAGE_HEADER);
    if (nonNull(generic)) {
        SimpMessageHeaderAccessor nativeAccessor = SimpMessageHeaderAccessor.wrap(generic);
        List<String> userIdValue = nativeAccessor.getNativeHeader("user-id");

        return isNull(userIdValue) ? null : userIdValue.stream().findFirst().orElse(null);
    }

    return null;
}

Trung Cao Tiến · Answer 2 · 2022-07-01T17:13:24.917

For the handleWebSocketConnectListener(SessionConnectedEvent event)

After using debug of Intellij, i discover this and it works!

MessageHeaderAccessor headerAccessor = 
     MessageHeaderAccessor.getAccessor(event.getMessage().getHeaders(), 
     MessageHeaderAccessor.class);
StompHeaderAccessor stompHeaderAccessor = MessageHeaderAccessor.getAccessor(
                (Message<?>) headerAccessor.getHeader("simpConnectMessage"),
                StompHeaderAccessor.class) ;
String token = stompHeaderAccessor.getNativeHeader("Authorization").get(0);

get native header when a user connects

2 Answers2