How to send message to a specific subscription over spring websocket STOMP?

问题

I am using STOMP over websockets with spring boot. Is there a possibility to send a message to a specific subscription? I subscribe to the STOMP endpoints using a STOMP header containing an id field according to the stomp documentation I want this id to be used to determine the clients who should receive a message, but spring seems not to use this id. I can not just use sendToUser because two clients can have the same user id e.g. if a user has two opened browser windows. Only one specific window should receive the message.

In the following example I have two connected clients which are using the same user, but different ids in the STOMP header.

Client1-ID: a32d66bf-03c7-47a4-aea0-e464c0727842

Client2-ID: b3673d33-1bf2-461e-8df3-35b7af07371b

In spring I have executed the following Kotlin code:

val subscriptions =  userRegistry.findSubscriptions {
            it.destination == "/user/topic/operations/$operationId/runs"
        }
        subscriptions.forEach{
            println("subscription id: ${it.id}");
            println("session id: ${it.session.id}");
            println("user id ${it.session.user.name}");
        }

The output:

subscription id: sub-7
session id: mcjpgn2i
user id 4a27ef88-25eb-4175-a872-f46e7b9d0564
subscription id: sub-7
session id: 0dxuvjgp
user id 4a27ef88-25eb-4175-a872-f46e7b9d0564

There is no sign of the id I have passed to the stomp header.

Is it possible to send a message to one specific subscription determined by the id I have passed with the header?

回答1:

I got it working.

First of all, there was something wrong with my client setup. I have set the subscription id in the connection header like this:

this.stompClient.webSocketFactory = (): WebSocket => new SockJS("/ws");
this.stompClient.connectHeaders = { id: subscriptionId };
this.stompClient.activate();

But the subscription header has to be set in the subscription header:

this.stompClient.subscribe(this.commonEndpoint,
        this.onMessageReceived.bind(this),
        { id: subScriptionId });

If I do this, spring is correctly using this id as the subscription id, instead of using some default like sub-7.

According to that thread I can send messages to specific sessions instead of user.

With the following code I can send a message to a specific subscription:

val subscriptions = userRegistry.findSubscriptions {
            it.destination == "/user/topic/operations/$operationId/runs"
        }
subscriptions.forEach {
    if(it.id === mySubscriptionId){
        val headerAccessor = 
        SimpMessageHeaderAccessor.create(SimpMessageType.MESSAGE)
        headerAccessor.sessionId = it.session.id
        headerAccessor.setLeaveMutable(true)

        simpMessagingTemplate.convertAndSendToUser(it.session.id,  
            "/topic/operations/runs", messageResponseEntity,
            headerAccessor.getMessageHeaders())

     }
}

来源：https://stackoverflow.com/questions/60488396/how-to-send-message-to-a-specific-subscription-over-spring-websocket-stomp

标签

Spring

websocket

stomp