If it is synchronous or transactional then don't use microservices. Plenty of things can be done asynchronously provided the use case is ok with eventual consis

If it is synchronous or transactional then don't use microservices. Plenty of things can be done asynchronously provided the use case is ok with eventual consistency or within a non urgent time limit. BTW now that the browser supports websockets (a bidirectional protocol the rest of the world had since the 70s!), you don't have to poll.