spring-boot - SSE emitters received timeout at client side onmessage

Question

I am writing a web which as client side and using spring boot to write for server side for SSE using SseEmitter. However, when client first connected to server side, I can see the debugger executed smoothly at server side, when upon return emitter, client side onmessage received timeout: message. Can guide me if I did anything wrong? below are my coding, for both server and client side.

server:

@RestController
@RequestMapping("/")
@RequiredArgsConstructor(onConstructor = @__(@Autowired))
public class RateDataController {
    
    private final CopyOnWriteArrayList<SseEmitter> emitters = new CopyOnWriteArrayList<>();

    @GetMapping(value = "/subscribe", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
    public SseEmitter subscribe() {
        SseEmitter emitter = new SseEmitter(Long.MAX_VALUE);
        try {
            emitter.send(emitter.event().name("INIT"));
        } catch (IOException e) {
            e.printStackTrace();
        }
        emitters.add(emitter);
        emitter.onCompletion(() -> emitters.remove(emitter));
        return emitter;
    }

Client side:

eventSource = new EventSource(
                'http://localhost:8080/subscribe')
            eventSource.onopen = (event) => {
                console.log('connection opened')
            }

            eventSource.onmessage = (event) => {
                console.log('result', event.data)
            }

Image on message received from server

Any advice will be appreciated. Thanks,

标签： spring-boottimeoutserver-sent-eventsemitter