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Re: ID for Immutable

From: Leif Hedstrom <leif@ogre.com>
Date: Mon, 7 Nov 2016 14:20:25 -0700
Cc: HTTP Working Group <ietf-http-wg@w3.org>
Message-Id: <901964AC-3423-4789-934F-3C583214ED85@ogre.com>
To: Patrick McManus <pmcmanus@mozilla.com>

> On Oct 26, 2016, at 3:02 PM, Patrick McManus <pmcmanus@mozilla.com> wrote:
> 
> [as individual]
> 
> FYI
> 
> A new version of I-D, draft-mcmanus-immutable-00.txt
> has been successfully submitted by Patrick McManus and posted to the
> IETF repository.


Interesting. Couple of quick thoughts with my proxy-server hat on.

1) Many (most?) reverse proxy servers has features to ignore e.g. Cache-Control: max-age=0, or Cache-Control: no-cache from the clients. Not doing so would really open up some ugly rat holes for cache busting. [See the ATS configs below].

2) As such, this new CC: immutable directive seems geared primarily towards user-agents and possibly for forward proxies?

3) I didn’t read particularly carefully, but would it make sense to specify exactly what headers a proxy would ignore in favor of CC: immutable? I’m thinking in my case, we’d honor a CC: immutable over some of our configuration options [again see below].

For 3), I believe most clients will send something like 

	Cache-Control: no-cache
	Pragma: no-cache

correct when doing a “force” revalidate? I understand that this is UA specific, but if we are going to say something about this for intermediaries, maybe worth pointing this out? If so, what about Cache-Control: max-age=0?

Cheers,

— leif

P.s
Apache Traffic Server settings (defaults):

	CONFIG proxy.config.http.cache.ignore_client_no_cache INT 1
	CONFIG proxy.config.http.cache.ignore_client_cc_max_age INT 1

P.P.s
Yes, we know this violates the RFC :-).
Received on Monday, 7 November 2016 21:20:56 UTC

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