[anon9001]

Pedantic, but: from the device's point of view, it's always a "pull". You can't "push" to something that's not publicly addressable.

From your app's point of view, you receive a "push" from the OS.

[burnished]

I think they are differentiating between systems that perform polling and systems that can receive interrupts (maybe not quite the right word here), I don't think that has anything to do with being publicly addressable here, in either case you sort of have to assume that devices can find each other before the difference even makes sense.