java spring websocket发送来自其他应用程序的回复

Question

I have two different java spring applications. First one sends a message using websocket and it works fine.

client:

var socket = new SockJS('http://localhost:8080/myapp/hello');
            stompClient = Stomp.over(socket);
            stompClient.connect({}, function(frame) {
                console.log('Connected: ' + frame);
                stompClient.subscribe('/topic/greeting', function(greeting){
                    console.log(greeting.body);
                    //showGreeting(JSON.parse(greeting.body).content);
                });
            });

Server:

@MessageMapping("/send/{widgetId}")
    public Greeting userMessage(@DestinationVariable String widgetId,
            UserMessageWrapper userMessageWrapper) throws Exception {
        dispatchMessage(widgetId, userMessageWrapper.getUserToken(),
                userMessageWrapper.getMessage(), userMessageWrapper.getUserAgent());
        return new Greeting("asdasdsa");
    }

It works fine, but I need to send a reply to this message from other java application on other server. I have a quartz job there and it scans db and sends replies to subscribed clients using websockets. I want every client to receive only message for him, no broadcasting.

public void callJSWebSocket(){
    SimpMessageHeaderAccessor headerAccessor = SimpMessageHeaderAccessor
            .create(SimpMessageType.MESSAGE);
    headerAccessor.setSubscriptionId("sub-0");
    headerAccessor.setLeaveMutable(true);

    messagingTemplate.convertAndSendToUser("user","/topic/greeting",
            "asdsadasd1212");
}

and configuration in both cases:

@Configuration
@EnableWebSocketMessageBroker

    public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {

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

        @Override
        public void registerStompEndpoints(StompEndpointRegistry registry) {
            registry.addEndpoint("/hello").setAllowedOrigins("*").withSockJS();
        }

    }

I don't understand how to send message properly from other application. I guess I need to retrieve and store sessionId somewhere and then use for replying. Also, should I create config and controller for replying and what I am doing wrong?

Answer 1

Fortunately I have managed to solve this situation. First, I didn't find a way to interact with page directly from other application and I believe that it's not possible, because connection is required. I decided to use a Jersey endpoint on first app that has a websocket connection to the page. So, the second app calls REST url of the first app and then first app sends websocket message.

IMPORTANT IMPORTANT!!!!!

If you have in your app a "/" context that mapped, for example, to spring-mvc, make it /mvc or anything else. Because if you have more than one context in spring (root and servlet contexts), spring websocket messaging infrastructure creates N sets of beans where N is number of your contents. So I faced a situation when WS session was registered in one context, but session check, convertAndSend method, etc, runned in other context. I spent some hours on that. If you see a situation when you can't send a message to subscribed session, please go to

org.springframework.messaging.simp.broker.DefaultSubscriptionRegistry#getSubscriptions(String destination, Message<?> message). 

And if you see that

subscriptionRegistry.getAllSubscriptions()

is empty, please check your "/" context and make it not "/".