Yeah, but that paper is from 2007, not exactly current, and back then
protobuf *was* closed source AFAIK.
ICE started somewhen in 2003, so it may not have been as known in 2007.
Plus FB would have to shell out license cost to ZeroC if they'd been
serious about using it.
It's an interesting thought though: "What if FB had use ICE?" :-)
cheers.