Re: p2: Expectation extensions

James M Snell <jasnell@gmail.com> Tue, 23 April 2013 15:24 UTC

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From: James M Snell <jasnell@gmail.com>
Date: Tue, 23 Apr 2013 08:22:16 -0700
Message-ID: <CABP7RbePyYdWmQjz-LyTan0acE5LWj3owpcZe9BWYfxfyBFAbw@mail.gmail.com>
To: Amos Jeffries <squid3@treenet.co.nz>
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Subject: Re: p2: Expectation extensions
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+1 ... what Amos said.

On Tue, Apr 23, 2013 at 6:57 AM, Amos Jeffries <squid3@treenet.co.nz> wrote:
> On 23/04/2013 7:22 p.m., Mark Nottingham wrote:
>>
>> p2 5.1.1 requires that an unrecognised expectation be replied to with a
>> 417 Expectation Failed.
>>
>> In my testing, it's fairly common for servers to ignore an unregistered
>> expectation (e.g., "foo").
>>
>> Given how many problems we already have with Expect, should we consider
>> disallowing further extensions here, and removing this requirement?
>
>
> So whats gained by making it an expectation if the expectation is ignored?
> nothing.
>
> Removing it also removes the fail-closed property of Expect:. I know the
> property is a great annoyance to new featrue rollout. But it does offer the
> concrete assurance that what is expected is supported which is quite useful
> when designing security related extensions. We have the Prefer header coming
> up to provide the expectation negotiation with fail-open semantics.
>
> So overall I think we keep this, the servers not implementing it are already
> non-conformant with Expect.
>
> Amos
>