- It's independent of the protocol. Each server can invent its own method. Personally I'm hoping servers/proxies will "upgrade" some HTTP/1.1 Link header to PUSH, e.g.:
Link: </style.css>; rel=preloadExcept for other applications trying to use the finite, and possibly expensive, bandwidth of the connection as a whole?
That sounds like it could be an issue on mobile devices. If I've got a 1GB data plan, I don't want you sending large files that I've already got cached. Even partially sending them could consume significant bandwidth given the latency involved.
The tradeoff is that you're introducing a round-trip for pushed resources to acknowledge that you want to receive the entire resource. That may or may not make sense, depending on the use case.
My biggest concern with HTTP/2 is that it's going to be difficult for web applications to organize their server push requests. It seems like it will definitely require updates to server app frameworks to make this tractable.
1. https://nghttp2.org/blog/2015/02/10/nghttp2-dot-org-enabled-... 2. https://code.google.com/p/mod-spdy/wiki/OptimizingForSpdy