Spring STOMP over WebSockets not scheduling heartbeats

Question

We have a Spring over WebSockets connection that we're passing a CONNECT frame:

CONNECT\naccept-version:1.2\nheart-beat:10000,10000\n\n\u0000

Which the handler acknowledges, starts a new session, and than returns:

CONNECTED
version:1.2
heart-beat:0,0

However, we want the heart-beats so we can keep the WebSocket open. We're not using SockJS.

I stepped through the Spring Message Handler:

StompHeaderAccessor [headers={simpMessageType=CONNECT, stompCommand=CONNECT, nativeHeaders={accept-version=[1.2], heart-beat=[5000,0]}, simpSessionAttributes={}, simpHeartbeat=[J@5eba717, simpSessionId=46e855c9}]

After it gets the heart-beat (native header), it sets what looks like a memory address simpHeartbeat=[J@5eba717, simpSessionId=46e855c9}]

Of note, after the broker authenticates:

Processing CONNECT session=46e855c9 (the sessionId here is different than simpSessionId)?

When running earlier TRACE debugging I saw a notice "Scheduling heartbeat..." or something to that effect...though I'm not seeing it now?

Any idea what's going on?

Thanks

I have found the explanation in the documentation:

SockJS Task Scheduler stats from thread pool of the SockJS task scheduler which is used to send heartbeats. Note that when heartbeats are negotiated on the STOMP level the SockJS heartbeats are disabled.

Are SockJS heartbeats different than STOMP heart-beats?

Answer 1

Yes SockJS heartbeats are different. Fundamentally the same thing but their purpose in the SockJS protocol are to ensure that the connection doesn't look like it's "dead" in which case proxies can close it pro-actively. More generally a heartbeat allows each side to detect connectivity issues pro-actively and clean up resources.

When using STOMP and SockJS at the transport layer there is no need to have both which is why the SockJS heartbeats are turned off if STOMP heartbeats are in use. However you're not using SockJS here.

You're not showing any configuration but my guess is that you're using the built-in simple broker which does not automatically send heartbeats. When configuring it you will see an option to enable heartbeats and you also need to set a task scheduler.

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {

    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
         // ...
    }

    @Override
    public void configureMessageBroker(MessageBrokerRegistry registry) {
        registry.enableStompBrokerRelay(...)
                .setTaskScheduler(...)
                .setHeartbeat(...);
    }

}