internal static Dal_XML_imp getInstance()
 {
     if (instance == null)
     {
         instance = new Dal_XML_imp();
     }
     return(instance);
 }
        public static IDL GetDL(string type)
        {
            switch (type)
            {
            case "lists":
                return(DLObject.getInstance());

            case "xml":
                return(Dal_XML_imp.getInstance());

            default:
                throw new Exception("No such type of DL object implementation exists (factory exception...)");
            }
        }