[Lecture] Ideal HTTP Perfor­mance

A common ques­tion about Server Push is “what if the client already has a copy in cache?” Because Push is inhe­rently specu­la­tive, there’s always the chance that you’re sending some­thing that the brow­ser doesn’t need.

HTTP/2 allows the client to cancel the push in this situa­tion, with a RESET_STREAM. Howe­ver, even then, there’s roughly a round trip’s worth of wasted data in flight that could have been used for better things. Remem­ber, the ideal is to send only the data that the client needs to show the page.

A propo­sed solu­tion for this is for the client to use a compact Cache Digest to tell the server what it already has in cache, so that the server knows what’s needed.

Bon article de Mark Nottin­gham sur HTTP 2, qui dépasse les notions de base qu’on voit partout. On y parle même un peu des évolu­tions de TCP.