Subject: [httpwg/http-extensions] [cache-digests] Avoid sending the digest when not used (#410)

From: HTTP issue updates <[email-masked]>
Date: Sat, 30 Sep 2017 05:57:59 +0000 (UTC)

While discussing this, I heard raised concerns that:
* Adding cache digest support as currently specced may result in sending the digest even in cases where it is not used. Since initially this is likely to be most cases, shipping support is likely to result in performance regressions.
* OTOH, a digest negotiation mechanism is likely to result in an RTT worth of delay before the digest reaches the server.

A mechanism to solve this may look something like:
* Client SETTING parameter that tells the server "I'm going to send a cache digest, wait for it". If this setting is not present, the server should not wait for a digest before pushing.
* Server SETTING parameter that tells the client "I really like to get a cache digest next time around"
* Client implementations SHOULD/MUST maintain server preference for future sessions, and MAY not send a cache digest if a past session with that server did not include a "I want a digest" SETTING parameter.
* On the very first connection to a server, the client's cache is empty, so not sending the digest in that case has no penalty.

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/httpwg/http-extensions/issues/410