A bit of context, in case you haven’t been keeping up with the real-time web craze:
RSSCloud is an… idea* for getting updates on RSS feeds to clients faster, while decreasing network load. In traditional RSS models, subscribers make an HTTP request every 10 minutes or so to a publisher to check for updates. In RSSCloud, a cloud server aggregates several feeds from authors. When feeds are changed, their authors send an HTTP request to the cloud server notifying them of the update. The cloud server contacts one or more subscribers of the feed, sending them a notice that the feed has changed. The subscribers then request the feed from the authors. Everyone gets their updates faster, and with fewer requests across the network.
When you subscribe to an RSSCloud server, you tell it several things about how to notify you of changes: