I've made some improvements to my #Fediverse history post. Thanks to @clacke for the corrections, keep 'em coming!
http://qttr.at/1r0f

@strypey @clacke adding a small bit of history - how/where the name "The Federation" was born: https://joindiaspora.com/posts/5022661 (note that @[email protected] proposed the term in that meaning)

Hope that's useful! :)
#KeepCalmAndFederate

ActivityStreams as practised in OStatus and pump.io are quite different although the concepts are similar. The first is an XML wrapper around Atom. The second is a JSON format which dispensed with all the Atom compatibility. The most recent (ASJLD2) variants include 'Linked Data' which provides machine readers with semantic clues as to the high level content of various fields or structures. There are enough differences that the formats aren't directly interchangeable.

If I recall there was a PubSub XMPP mechanism in XMPP which is different that PubSubHubBub; which is a subscribe/push protocol for feeds that was developed at Google.