How does FeedSync work?
FeedSync defines new XML elements that add synchronization information to items in an RSS or Atom feed. These new elements enable FeedSync applications conforming to the specification to implement bidirectional feeds. In other words, two endpoints can mutually publish and subscribe to each other’s feeds. When changes are made in one endpoint, they are propagated to the other and vice versa. The new XML elements described in FeedSync enable feed readers and publishers to generate and process incoming item changes in a manner that enables consistency to be achieved. In order to accomplish this, FeedSync introduces concepts such as per-item change history (to manage item versions and update conflicts) and tombstones (to propagate deletions, and un-deletions). FeedSync also allows preservation of conflicting data to preserve data state for later resolution by end users.
