interface ItemsImporterInterface

interface ItemsImporterInterface {
    
    /**
     * Updates the feed items by triggering the import process.
     *
     * This process can be slow and lengthy because it relies on network
     * operations. Calling it on performance critical paths should be avoided.
     *
     * @param \Drupal\aggregator\FeedInterface $feed
     *   The feed which items should be refreshed.
     *
     * @return bool
     *   TRUE if there is new content for the feed FALSE otherwise.
     */
    public function refresh(FeedInterface $feed);
    
    /**
     * Deletes all imported items from a feed.
     *
     * @param \Drupal\aggregator\FeedInterface $feed
     *   The feed that associated items should be deleted from.
     */
    public function delete(FeedInterface $feed);

}