sendingDataMessageInFCM.php

<?php
    public function push($user_id, $message)
    {
        define('API_ACCESS_KEY', '');
        define('SENDER_ID', '');

        $headers = array
        (
            'Authorization: key=' . API_ACCESS_KEY,
            'Sender: id=' . SENDER_ID,
            'Content-Type: application/json; charset=utf-8'
        );

        $fcmMsg = array(
            'text' => ($message),
            'title' => ('title'),
            'sound' => "default",
            'color' => "#203E78"
        );

        $fields = array(
            'to' => $singleID->firebase_token,
            'priority' => 'high',
            'data' => $fcmMsg
        );

        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, 'https://android.googleapis.com/gcm/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);

    }

?>