Observer Design Pattern example

observer.php

<?php


class HookService
{

    public function TrackingHookService()
    {
        $subscriber1 = new Subscriber("http://listener1.com/listenurl",000);
        $subscriber2 = new Subscriber("http://listener2.com/listenurl",999);
    
        $eventPublisher = new EventPublisher();
        $eventPublisher->attach($subscriber1);
        $eventPublisher->attach($subscriber2);
    
        $eventPublisher->notify();
    }

}


class Subscriber
{
    public $listenerPath,$eventCode;
    public function __construct($listenerPath,$eventCode)
    {
        $this->$listenerPath = $listenerPath;
        $this->eventCode = $eventCode;
    }

    public function update()
    {
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $this->listenerPath);
        curl_setopt($ch, CURLOPT_HEADER, TRUE);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
        curl_setopt($s,CURLOPT_POST,true);
        curl_setopt($s,CURLOPT_POSTFIELDS,["eventCode"=>$this->eventCode]);
        curl_exec($ch);
        curl_close($ch);
    }
}

class EventPublisher
{
    private $subScribers=[];

    public function attach(Subscriber $subscriber)
    {
        $subscriber[] =$subscriber;
    }
    public function detach($index)
    {
        $subscriber[] =$subscriber;
    }

    public function notify()
    {
        foreach ($this->subScribers as $subscriber) 
        {
            $subscriber->update();
        }
    }
}