static DatabaseManager()
        {
            s_DatabaseHashtable = new Dictionary<string,Database>();
            s_FileChangeHandler = new FileSystemChangeEventHandler(500);
            s_FileChangeHandler.ActualHandler += new FileSystemEventHandler(OnFileChanged);
            _commonConfigInstance = DbInstanceManager.CreateDbInance();

            // set up file system watcher
            string databaseFolder = Path.GetDirectoryName(_commonConfigInstance.DatabaseConfigFile);
            string databaseFile = Path.GetFileName(_commonConfigInstance.DatabaseConfigFile);
            s_Watcher = new FileSystemWatcher(databaseFolder);
            s_Watcher.Filter = databaseFile;
            s_Watcher.NotifyFilter = NotifyFilters.LastWrite | NotifyFilters.CreationTime;
            s_Watcher.Changed += new FileSystemEventHandler(s_FileChangeHandler.ChangeEventHandler);
            s_Watcher.EnableRaisingEvents = true;

            // load database
            s_DatabaseHashtable = LoadDatabaseList();
        }
        static DataCommandManager()
        {
            _commonConfigInstance = DbInstanceManager.CreateDbInance();
            s_FileChangeHandler = new FileSystemChangeEventHandler(FILE_CHANGE_NOTIFICATION_INTERVAL);
            s_FileChangeHandler.ActualHandler += new FileSystemEventHandler(Watcher_Changed);

            s_DataFileFolder = Path.GetDirectoryName(_commonConfigInstance.DataCommandFileListConfigFile);

            s_CommandSyncObject = new object();
            s_CommandFileListSyncObject = new object();

            if (s_DataFileFolder == null
                || !Directory.Exists(s_DataFileFolder))
            {
                return;
            }

            s_Watcher = new FileSystemWatcher(s_DataFileFolder);
            s_Watcher.NotifyFilter = NotifyFilters.LastWrite | NotifyFilters.CreationTime;
            s_Watcher.Changed += new FileSystemEventHandler(s_FileChangeHandler.ChangeEventHandler);
            s_Watcher.EnableRaisingEvents = true;

            UpdateAllCommandFiles();
        }