* Default constructor.
     */
    public AbstractDataStore() {
        // nothing
    }

    /**
     * Register this data store.
     */
    public void register() {
        ComponentUtil.getDataStoreFactory().add(getName(), this);
    }

    /**
     * Get the name of this data store.
     * @return The name of this data store.
     */
    protected abstract String getName();

    @Override

         * deletes old documents if configured to do so.
         */
        protected void process() {
            final DataStoreFactory dataStoreFactory = ComponentUtil.getDataStoreFactory();
            dataStore = dataStoreFactory.getDataStore(dataConfig.getHandlerName());
            if (dataStore == null) {
                logger.error("DataStore({}) is not found.", dataConfig.getHandlerName());