public static function unpack(& $xpdo, $from, $to, $state = xPDOTransport::STATE_PACKED) {
        $manifest= null;
        if ($state !== xPDOTransport::STATE_UNPACKED) {
            $resources = xPDOTransport::_unpack($xpdo, $from, $to);
        } else {
            $resources = true;
        }
        if ($resources) {
            $manifestFilename = $to . basename($from, '.transport.zip') . '/manifest.php';
            if (file_exists($manifestFilename)) {
                $manifest= @include ($manifestFilename);
            } else {
                $xpdo->log(xPDO::LOG_LEVEL_ERROR, "Could not find package manifest at {$manifestFilename}");
            }
        }
        return $manifest;
    }