如何使用Firebase和PHP向使用我的应用安装的所有设备发送通知？

I'm making an existing application which includes notification when there is new content.

Notification is sent to all the gadgets that have installed the application.

How to do it using FCM and PHP?

Here is the PHP code to send notification using FCM.

<?php
define('API_ACCESS_KEY', ''); // API access key from Firebase Console
$registrationIds = array(''); //Token IDs of devices

$msg = array
(
    'text'  => 'Test Text',
    'title'     => 'Test Title',
);

$fields = array
(
    'to'    => $registrationIds[0],
    'notification'      => $msg,
    "priority"=> "high"
);

$headers = array
(
    'Authorization: key=' . API_ACCESS_KEY,
    'Content-Type: application/json',
);

$ch = curl_init();
curl_setopt( $ch,CURLOPT_URL, 'https://fcm.googleapis.com/fcm/send' );
curl_setopt( $ch,CURLOPT_POST, true );
curl_setopt( $ch,CURLOPT_HTTPHEADER, $headers );
curl_setopt( $ch,CURLOPT_RETURNTRANSFER, true );
curl_setopt( $ch,CURLOPT_SSL_VERIFYPEER, false );
curl_setopt( $ch,CURLOPT_POSTFIELDS, json_encode( $fields ));
$result = curl_exec($ch );
curl_close( $ch );
echo $result;
?>