Observables

Disposable.php

<?php

interface Disposable {
    public function dispose();
}

Observable.php

<?php

interface Observable {
    /**
     * @return Disposable
     */
    public function subscribe(Observer $observer);
}

Observer.php

<?php

interface Observer {
    public function onNext();
    public function onError(\Exception $error);
    public function onCompleted();
}