RFC 2778 describes the term "presentity" as follows:
Presentity (presence entity): provides presence information to a presence service.
This seems straightforward if inelegant. So imagine my surprise when, in discussing the nature of presentities during one of the meetings of the SIMPLE WG at IETF 60 yesterday, it was asserted that a presentity is generally and correctly understood to be a human being -- at which point I got up to the mic and opined that anyone who seeks to limit presentities to human beings is engaging in speciesism. There was a smattering of nervous laughter but I think most people thought I was joking.
I was not joking. Herewith my explanation.
A presentity is an entity that provides presence. In the context of a network, an entity is any addressable thing on the network. In the context of a communications technology, presence is, at root, a boolean indication of whether or not an entity is available for communication. What kind of things might be available for communication over a network? People, yes. But not just people: bots, chatrooms, applications, services, routers, servers, firewalls, gateways, appliances, devices, and much else besides can be networked for some form of communication. Is the firewall or router or web server up and running? That's presence. Is the chatroom functioning? That's presence. Is the bot able to provide answers right now? That's presence. Is the pubsub service sending out Atom/RSS feeds? That's presence. Is the workflow application down? That's presence. Is the coffee maker empty? That's presence. Is the cat on the mat? That's presence.
Thus my charge of speciesism. Any entity that could communicate or provide information on a network is potentially a presentity. Limiting presence to humans is misguided and unnecessary.
Presence: it's not just for humans anymore.