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RE: Making Implicit C-E work.

From: <K.Morgan@iaea.org>
Date: Sat, 17 May 2014 18:10:17 +0000
To: <matthew@kerwin.net.au>
CC: <ietf-http-wg@w3.org>, <C.Brunhuber@iaea.org>, <jgraettinger@chromium.org>, <martin.thomson@gmail.com>, <grmocg@gmail.com>, <mnot@mnot.net>
Message-ID: <0356EBBE092D394F9291DA01E8D28EC20112D9E021@sem002pd.sg.iaea.org>
On Saturday,17 May 2014 01:39, Matthew Kerwin wrote:

> On May 15, 2014 9:42 PM, <K.Morgan@iaea.org> wrote:

>> ... [Matthew's suggestion to lift the MUST requirement for intermediaries to decompress]

>> only makes sense _if_ you are assuming acceptance of Roberto's proposed

>> "uncompressed-*" headers solution. Otherwise this doesn't solve any of the problems

>> brought up by Matthew, Julian, myself and others with respect to etag, no-transform,

>> metadata within the entity body, etc...

>

> ... Right now a server is well within its rights to completely ignore any and all Accept-* headers;



I disagree. According to 'Section 5.3.4 Accept-Encoding' of HTTP-p2 [1], only if a client does not include an Accept-Encoding header, then a server can choose any encoding…



A request without an Accept-Encoding header field implies that the

user agent has no preferences regarding content-codings.  Although

this allows the server to use any content-coding in a response, it

does not imply that the user agent will be able to correctly process

all encodings. [1]



Furthermore, an empty Accept-Encoding field implies identity is the only acceptable coding...



An Accept-Encoding header field with a combined field-value that is

empty implies that the user agent does not want any content-coding in

response.  If an Accept-Encoding header field is present in a request

and none of the available representations for the response have a

content-coding that is listed as acceptable, the origin server SHOULD

send a response without any content-coding. [1]



It says nothing about being able to completely ignore the Accept-Encoding header.



So I still stand behind my statement that lifting the MUST requirement for gateway decompression doesn’t solve any of the problems.





> it's not the best for interop, but it's legal within the spec (406 might be better, but also not always great for interop).

> The "MUST decompress" effectively made gateways act as origins for certain responses,

> but they didn't have a choice about how to deal with this interop issue. By not saying anything we grant them the choice of decompressing, or sending compressed, or 406ing.



> I still definitely prefer not introducing implicit support in the first place.



Agreed.



[1] http://tools.ietf.org/html/draft-ietf-httpbis-p2-semantics-26#section-5.3.4






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Received on Saturday, 17 May 2014 18:11:17 UTC

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