Askar Ibragimov Askar Ibragimov - 2 months ago 49
Java Question

Send STOMP ERROR from Spring Websocket program

I have a Spring Websocket Stomp application that accepts SUBSCRIBE requests.

In application I have a handler for SUBSCRIBE, that is,

@Component
public class SubscribeStompEventHandler implements ApplicationListener<SessionSubscribeEvent> {

@Override
public void onApplicationEvent(SessionSubscribeEvent event) {}
}


that I use to validate subscription.

I would check something in the onApplicationEvent and send STOMP ERROR message back to client from this function.

I found this recipe How to send ERROR message to STOMP clients with Spring WebSocket? but I need to understand how to get outboundChannel.

I tried also the following code:

public void sendStompError(SimpMessagingTemplate simpMessagingTemplate, String sessionId, String topic, String errorMessage) {

StompHeaderAccessor headerAccessor = StompHeaderAccessor.create(StompCommand.ERROR);
headerAccessor.setMessage(errorMessage);
headerAccessor.setSessionId(sessionId);
headerAccessor.setLeaveMutable(true);
simpMessagingTemplate.convertAndSendToUser(sessionId, topic, new byte[0], headerAccessor.getMessageHeaders());
}


and I tried topic to be some subsciption topic and /queue/error topic. However I did not see messages propagating to client.

In Client, I use:

stompClient.connect(headers
, function (frame) {
console.log("Conn OK " + url);
}, function (error) {
console.log("Conn NOT OK " + url + ": " + JSON.stringify(error));
});
}


and my goal is to have function(error) called when I send STOMP ERROR.

Please advice me how exactly I can send proper STOMP ERROR, e.g. by getting Outboundchannel.

Answer

You can send ERROR Message like this:

StompHeaderAccessor headerAccessor = StompHeaderAccessor.create(StompCommand.ERROR);
headerAccessor.setMessage(error.getMessage());
headerAccessor.setSessionId(sessionId);
this.clientOutboundChannel.send(MessageBuilder.createMessage(new byte[0], headerAccessor.getMessageHeaders()));

The following is just enough to inject that clientOutboundChannel:

 @Autowired
 @Qualifier("clientOutboundChannel")
 private MessageChannel clientOutboundChannel;

Just because clientOutboundChannel bean is declared in the AbstractMessageBrokerConfiguration.

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