The publish operator is a thin wrapper around the multicast operator. It calls multicast, passing a Subject.
An observable is cold if the producer of its notifications is created whenever an observer subscribes to the observable. For example, a timer observable is cold; each time a subscription is made, a new timer is created.
An observable is hot if the producer of its notifications is not created each time an observer subscribes to the observable. For example, an observable created using fromEvent is hot; the element that produces the events ex…