W3C home > Mailing lists > Public > ietf-http-wg@w3.org > July to September 2011

Re: Expect header 'understand' vs 'meet'

From: Julian Reschke <julian.reschke@gmx.de>
Date: Wed, 07 Sep 2011 22:09:00 +0200
Message-ID: <4E67CF5C.1080604@gmx.de>
To: Jan Algermissen <jan.algermissen@nordsc.com>
CC: HTTP Working Group <ietf-http-wg@w3.org>
On 2011-09-07 22:03, Jan Algermissen wrote:
> Hi Julian,
>
>
> On Sep 7, 2011, at 9:58 PM, Julian Reschke wrote:
>
>> On 2011-09-07 21:38, Jan Algermissen wrote:
>>> Dear WG,
>>>
>>> I have a question on the Expect header section 9.2 in HTTPbis 16[1]
>>>
>>> Is my understanding correct:
>>>
>>> 1. A proxy that finds an expectation extension in the Expect header that it does understand but cannot meet must respond 417
>>> 2. A proxy that finds an expectation extension in the Expect header that it does not understand ignores the extension
>>>
>>>
>>> Jan
>>>
>>> [1] http://www.ietf.org/id/draft-ietf-httpbis-p2-semantics-16.txt
>>
>> "The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy MUST return a 417 (Expectation Failed) status code if it receives a request with an expectation that it cannot meet."
>>
>> I think that implies 417 for unknown extensions; how would the proxy "meet" the expectation when it doesn't know what it is?
>
>
> fair enough.
>
> But this means an extension can only be successfully defined and used when all intermediaries understand it - which is: never.
>
> Or am I getting this wrong?
> ...

No, that's unfortunately correct. Maybe we need to mention it.

Best regards, Julian
Received on Wednesday, 7 September 2011 20:09:30 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Friday, 27 April 2012 06:51:47 GMT