/**
*! @function instance
* @abstract Creates non-deserializing, non-cloneable instance object
* @param configuration array - server, username, password, database
* @return Singleton - Singleton object
*/
public static function instance($configuration)
{
if (!isset(self::$instance) || !is_null(self::$instance)) {
$c = __CLASS__;
self::$instance = new self($configuration);
}
return self::$instance;
}