public IsolatedStorageIndexInput(System.IO.IsolatedStorage.IsolatedStorageFile dir, string name)
        {
            try
            {
                _file = dir.OpenFile(name, FileMode.Open);
            }
            catch (InvalidOperationException e)
            {
                throw new AlreadyClosedException(e.Message);
            }

        }
 internal Stream OpenStream(System.Web.VirtualPath virtualPath)
 {
     return virtualPath.OpenFile();
 }