Real time notifications in spring boot web socket

Question

In my application, I need to send real time notifications to a specific user. My WebSocketConfig class is as below,

    @Configuration
    @EnableWebSocketMessageBroker
    public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {
        @Override
        public void registerStompEndpoints(StompEndpointRegistry stompEndpointRegistry) {
            stompEndpointRegistry.addEndpoint("/websocket-example")
                    .withSockJS();
        }

        @Override
        public void configureMessageBroker(MessageBrokerRegistry registry) {
            registry.enableSimpleBroker("/topic");
    }
}

Most of the time information will be sent by the server side. So I have not set the application destination.

In the client side, I am subscribing to the destination '/topic/user`,

function connect() {
    var socket = new SockJS('/websocket-example');
    stompClient = Stomp.over(socket);
    stompClient.connect({}, function (frame) {
        setConnected(true);
        console.log('Connected: ' + frame);
        stompClient.subscribe('/topic/user', function (greeting) {
//            showGreeting(JSON.parse(greeting.body).content);
console.log("Received message through WS");
        });
    });
}

In one of my RestController I have a method which broadcasts the message to all connected clients.

    @GetMapping("/test")
    public void test()
    {
        template.convertAndSend("/topic/user", "Hurray");
    }

Until this part everything works fine. I receive the message and is logging to the console.

Now If I want to send the notification only to specific users, I have to use template.convertAndSendToUser(String user, String destination, String message). But I am not understanding what I should pass to the user parameter. Where and when will I get the user?

I went through couple of questions related to this, but I am not understanding the concepts clearly.

Are you using spring security? – Solace Sep 22 '18 at 04:10 — Solace, Sep 22 '18 at 04:10

score 2 · Answer 1 · answered Sep 18 '18 at 13:20

Before sending any messages to a user you need to authenticate it by the server first. There are different ways for doing this. Spring Security is a key phrase here

https://docs.spring.io/spring-security/site/docs/current/guides/html5/helloworld-boot.html

When authentication is completed you can simply get user name by calling:

Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
String currentPrincipalName = authentication.getName();

https://www.baeldung.com/get-user-in-spring-security

score 0 · Answer 2 · answered Sep 09 '18 at 16:43

0

This username is part of a java.security.Principal interface. Each StompHeaderAccessor or WebSocket session object has an instance of this principle and you can get the username from it. it is not generated automatically. It has to be generated manually by the server for every session.

You can check here for more info about generating a unique id for every session.

then use like this:

@MessageMapping('/test')
public void test(SimpMessageHeaderAccessor sha)
{
  String userName = sha.session.principal.name;
  template.convertAndSend(userName, '/topic/user', "Hurray");
}

answered Sep 09 '18 at 16:43

Devratna

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I can access `SimpMessageHeaderAccessor` in a method annotated with `@MessageMapping('/test')`. But I am not receiving data from client side. I should be able to send notification to any user from any method. – Virat Sep 09 '18 at 17:51
you have to maintain a unique id for every session from client request and then use `convertAndSend` method to push notification for a specific client with their session id that you assigned to same. – Devratna Sep 10 '18 at 08:25
And where will I get that Id? Can you please edit your answer accordingly – Virat Sep 10 '18 at 09:24
take reference from https://stackoverflow.com/questions/37853727/where-user-comes-from-in-convertandsendtouser-works-in-sockjsspring-websocket – Devratna Sep 11 '18 at 14:23

Real time notifications in spring boot web socket

2 Answers2