RSSCloud Vs. PubSubHubbub: Why The Fat Pings Win. A PubSubHubbub advocate explains the differences between the two proposals: most importantly, PubSubHubbub includes the actual new content with the “fat ping” whereas RSSCloud just notifies you that you should poll the RSS feed, leading to a potential thundering herd. I’m still hoping one of those specs will detail a way in which they can be used for scalable regular WebHook-style notifications without any feed infrastructure at all.