While I think there's going to be a place for APIs to use async bidirectional communication (e.g. pretty much anything people use webhooks for) I don't think it makes sense to shoehorn in 'REST' (which in the quick start, is more RPC than REST). REST makes sense for HTTP, and I think something else (I don't know what) will make more sense for websockets. Maybe this is a good bridge to something better though.