protected static function getParams(array $arg_params)
    {
        $return = array();
        //validate params
        $data = array(
            'amount',
            'transaction_id',
            'customer_id',
            'security_token',
            'customer_ip'
        );
        foreach ($data as $key) {
            if(!empty($arg_params[$key])){
                $return[$key] = $arg_params[$key];
            }
        }

        return $return;
    }