Interacting with Publish-Subscribe

Let's imagine we're sitting with Marty McFly in the DeLorean waiting for the exact time to put his foot on the accelerator and head back to the future. To get this information, he has been told by Doc Brown to use an XMPP pubsub system because Doc knows it's real-time and reliable.

First, Marty would need to find the XMPP server, discover where he can get information from it, subscribe to the source of the information, get some history, and then start receiving real-time updates. Meanwhile, Doc would need to have these pieces of information created and published to the server.