private function getParameters()
    {
        $getKeys = array_keys($_GET);
        $params = null;
        // read parameters "param:name=value"
        foreach ($getKeys as $key) {
            if (substr($key, 0, 6) == "param:") {
                $paramName = substr($key, 6);
                $paramValue = $_GET[$key];
                $params[$paramName] = $paramValue;
            }
        }
        return $params;
    }