support of DeferredResult / DeferredResponse object in webserver, (useful for long pollingor for ‘long result, like writing a very large file in chunks (without owning a thread).
Main idea is you have associated (to connection) list of active ‘deferred responses’. PROBABLY also maintain timeout with each of them. When timeout happens, they get one last warning to complete, and if not are closed down (unless they somehow extend themselves). And can have other things trigger finsihsing the deferred responses (like a condition variable associated with each one that can be ‘signaled’). Then for long polling, have change in data wakeup all waiting deferred tasks? (or at least the ones that were waiting on this).
Read up on java deferred task – e.g https://www.baeldung.com/spring-deferred-result;