public interface AsyncCallback<T>
invoke(T)will eventually lead to the registered handler being called.
This holder has the same lifecycle as a stream and cannot be used before materialization is done.
Typical use cases are exchanging messages between stream and substreams or invoking from external world sending event to a stream
void invoke(T t)
For cases where it is important to know if the notification was ever processed or not see [AsyncCallback#invokeWithFeedback}
The method returns directly and the returned future is then completed once the event
has been handled by the operator, if the event triggers an exception from the handler the future
is failed with that exception and finally if the operator was stopped before the event has been
handled the future is failed with
The handling of the returned future incurs a slight overhead, so for cases where it does not matter
to the invoking logic see