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Re: RFC: draft-brown-device-stock-ua-00.txt

From: John Kemp <john@jkemp.net>
Date: Wed, 14 Nov 2012 10:28:25 -0500
Cc: ietf-http-wg@w3.org
Message-Id: <FBAFC4F1-E83C-4A4D-8F9B-AA2D7C7CAF76@jkemp.net>
To: Ilya Grigorik <ilya@igvita.com>
On Nov 9, 2012, at 3:32 PM, Ilya Grigorik wrote:

> On Fri, Nov 9, 2012 at 11:33 AM, John Kemp <john@jkemp.net> wrote:
> One question - what happens in the presence of an intermediary? SHOULD an intermediary pass on the Client-hints HTTP header, if sent by a client?
> Yes. If the intermediary is the doing the adaptation based on the hint, then theoretically it could drop the header when forwarding the request (but more likely, just pass it along).

Here's what the Prefer header (http://tools.ietf.org/html/draft-snell-http-prefer-17 which I just happened to take a look at based on the word 'prefer') says about intermediaries:

"The Prefer header field is end-to-end and SHOULD be forwarded by a by a proxy if the request is forwarded. proxy if the request is forwarded unless Prefer is explicitly identified as being hop-by-hop using the Connection header field defined by [I-D.ietf-httpbis-p1-messaging], Section 6.1."

"  In various situations, a proxy might determine that it is capable of honoring a preference independently of the server to which the request has been directed. For instance, an intervening proxy might be capable of providing asynchronous handling of a request using 202 Accepted responses independently of the origin server. Such proxies can choose to honor the "respond-async" preference on their own despite whether the origin is capable or willing to do so."

By the way, I see overlap between the Prefer header, the Device-Stock-UA header and the Client-hints header. Has anyone else looked at these specs. to see why one would use one over the other, or why there is a need for 3 (in addition to the prior work)?

> ig
Received on Wednesday, 14 November 2012 15:28:51 UTC

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