What are the correct practices for manipulating events in PHP?

I've created some classes and an interface to handle events for a small MVC application. My intention is to implement the Observer pattern, but I do not know if you agree, since I still confuse it with PHP. In the following code, did I do it the right way, or could it cause some maintenance problem in the future?

<?php
# Interface do listener 
interface ActionListener {
    public function actionPerformed(ActionEvent $e);
}

# O evento
class ActionEvent {

    private $eventSource;
    private $id;
    private $command;
    private $time;

    public function __construct($eventSource, $id, $command = '') {
        $this->eventSource = $eventSource;
        $this->id = $id;
        $this->command = $command;
        $this->time = time();
    }

    public function getEventSource() {
        return $this->eventSource;
    }

    public function getID() {
        return $this->id;
    }

    public function getCommand() {
        return $this->command;
    }

    public function getTime() {
        return $this->time;
    }
}

# Uma fonte de eventos.
class EventSource {

    private $listeners = [];

    public function notify($id, $command = '') {
        $event = new ActionEvent($this, $id, $command);
        foreach ($this->listeners as $actual) {
            $actual->actionPerformed($event);
        }
    }

    public function addActionListener(ActionListener $object) {
        $this->listeners[] = $object;
    }
}