index.php

<?php


$registrationIds = array( $_POST['id'] );
$title =  $_POST['title'] ;
$subtitle = $_POST['subtitle'] ;
$data = $_POST['data'] ;

// prep the bundle
$msg = array
(
	'title'		=> $title,
	'subtitle'	=> $subtitle,
	'data'	        => $data
);

$fields = array
(
	'registration_ids' 	=> $registrationIds,
	'data'			=> $msg
);
 
$headers = array
(
	'Authorization: key = put...your..api_key..here...Find...out...it..from...google-services.json file ',
	'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;
?>