Scoped Spring events possible?

Question

The Spring event mechanism supports publishing application events and listening to these events within Spring components via the @EventListener annotation. However, I cannot find anything about sending events within a specific scope in the documentation. My specific need for Vaadin is:

• in context of a user interaction, send an event (e.g. logged-in event)
• this event should only be consumed by beans in same @UIScope, i.e. other user UIs shouldn't be effected

Is that possible? NOTE: This is not really specific to Vaadin. I could also ask how it would be done with Spring web mvc request scope.

Answer 1

TL;DR : I think it already works as you wanted it

Long version :

The documentation is somewhat unclear about this, but having tried a simple test :

A controller that publishes events :

@Controller
public class FooController {
    @Autowired
    private ApplicationEventPublisher publisher;

    @GetMapping("/fireEvent")
    public void fireEvent() {
        publisher.publishEvent(new FooEvent(this));
    }
}

And a scoped bean that listens :

@Scope(value = WebApplicationContext.SCOPE_REQUEST)
@Component
public class FooListener {
    @EventListener(FooEvent.class)
    public void listen() {
         System.out.println("I'm listening. PS : I am "+this.toString());
    }
}

And when running two concurrent requests, only the listener scoped to the the same httprequest gets the event.

---

My interpretation (without having looked at it really deeply, so take it with a grain of salt) :

It seems to me that the ApplicationEventMulticaster's ListenerRetriever uses the BeanFactory to get the beans that were previously registered as listeners (by their names). And obviously, the factory will return a bean in the current scope.