Under-the-Hood_Stills_1920x1080_Final

When someone opens up Facebook, regardless of the front-end interface (e.g., iPhone, Android phone, web browser), the interface will send a request to a Web/PHP (front-end) layer, which then queries the feed aggregator (back-end layer). After accepting a request from the front end, the feed aggregator fetches actions and objects, along with an object summary, from the feed leaf databases so that it can process, aggregate, rank, and return the resulting list of ranked FeedStories to the front end for rendering.