static function installationID()
    {
        if ( !empty( self::$InstallationID ) )
        {
            return self::$InstallationID;
        }
        $db = eZDB::instance();

        $resultSet = $db->arrayQuery( 'SELECT value FROM ezsite_data WHERE name=\'ezfind_site_id\'' );

        if ( count( $resultSet ) >= 1 )
        {
            self::$InstallationID = $resultSet[0]['value'];
        }
        else
        {
            self::$InstallationID = md5( time() . '-' . mt_rand() );
            $db->query( 'INSERT INTO ezsite_data ( name, value ) values( \'ezfind_site_id\', \'' . self::$InstallationID . '\' )' );
        }

        return self::$InstallationID;
    }