As we discussed in the previous chapter, the publisher is responsible for the generation of unbounded asynchronous events, and it pushes them to the associated subscribers. It is represented by the org.reactivestreams.Publisher interface, as follows:
public interface Publisher<T> {
public void subscribe(Subscriber<? super T> s);
}
The interface provides a single subscribe method. The method is invoked by any party that is interested in listening to events published by the publisher. The interface is quite simple, and it can be used to publish any type of event, be it a UI event (like a mouse-click) or a data event.
Since the interface is simple, let's add an implementation for our custom FibonacciPublisher:
public class FibonacciPublisher ...
