PHP PremiumManager::return_error示例

/**
 * Copyright (C) 2013 Ulteo SAS
 * http://www.ulteo.com
 * Author David PHAM-VAN <*****@*****.**> 2013
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; version 2
 * of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 **/
require_once dirname(__FILE__) . '/../includes/core.inc.php';
if (class_exists("PremiumManager")) {
    if (!array_key_exists('message', $_REQUEST)) {
        Logger::error('main', '(client/sign) - no message given');
        echo PremiumManager::return_error(1, 'No message given');
        die;
    }
    PremiumManager::sign($_REQUEST['message']);
}
$protocol = isset($_SERVER['SERVER_PROTOCOL']) ? $_SERVER['SERVER_PROTOCOL'] : 'HTTP/1.0';
header("{$protocol} 501 Not Implemented");
exit(0);