/**
  * Implementation of the singleton design pattern
  * See http://www.talkphp.com/advanced-php-programming/1304-how-use-singleton-design-pattern.html
  * 
  * @return SessionWrapper
  */
 public static function getInstance()
 {
     if (null === self::$_instance) {
         self::$_instance = new self();
     }
     return self::$_instance;
 }
	public static function getId() {
		if (null === self::$_instance) {
            self::$_instance = new self();
        }
        return Zend_Session::getId();
    }