Feeds is a hosted realtime pubsub API; your servers publish items to feeds, and clients receive those items in realtime. The published items are stored, so in addition Feeds provides the following features:
- Clients automatically receive previously published items when they subscribe, avoiding an extra call to the database and the possibility of missed or duplicated items
- If a client disconnects and reconnects, the subscription will be automatically resumed from the last message they received so they don't miss anything
- Since published items are stored, the client can query items in a feed for a paginated view
This makes Feeds an excellent fit for building systems like user notifications, comment streams, activity streams, realtime graphs, and many more.
Here's the basic architecture of the Feeds service:
Run through the getting started guide to try it out, or check out the more in-depth tutorial. The Feeds model page gives a more detailed overview of the concepts required to fully understand the Feeds API.