Simple Update Protocol, or SUP, was a protocol developed by FriendFeed to simplify and speed up RSS and Atom. A few websites supported SUP for a while, meaning that updates from their services appeared in FriendFeed within seconds, until support was dropped, and eventually FriendFeed itself shutdown 2015-04-09.[1] These sites include Disqus, Identi.ca, reddit.
Contents
Brightkite
Brightkite supported SUP but was itself shutdown in April 2012.
YouTube
YouTube supported SUP according to YouTube v2 API SUP documentation, yet as that reference says "The YouTube Data API (v2) has been officially deprecated as of March 4, 2014."
YouTube Data API (v3) supports push notifications via PubSubHubbub instead and no longer has SUP section.
References
Simple Update Protocol Wikipedia(Text) CC BY-SA