Re: Proposed IESG Statement on the use of the “Updates” header

Brian E Carpenter <brian.e.carpenter@gmail.com> Thu, 13 September 2018 21:00 UTC

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Subject: =?UTF-8?Q?Re:_Proposed_IESG_Statement_on_the_use_of_the_=e2=80=9cUp?= =?UTF-8?B?ZGF0ZXPigJ0gaGVhZGVy?=
To: Benjamin Kaduk <kaduk@mit.edu>
Cc: Ben Campbell <ben@nostrum.com>, ietf@ietf.org, The IESG <iesg@ietf.org>
References: <59F6DED7-8D39-4206-8268-22AB6A99A876@nostrum.com> <9a505c33-3327-a13f-f5ce-4fac360169b1@nostrum.com> <5d328d01-1ed6-3d0a-d250-d70fdaad00ff@gmail.com> <20180913133411.GX48265@kduck.kaduk.org>
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Message-ID: <6c53ae18-a827-aff6-d0b2-0d04f95ed106@gmail.com>
Date: Fri, 14 Sep 2018 08:59:53 +1200
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Hi Ben,

On 2018-09-14 01:34, Benjamin Kaduk wrote:
> On Wed, Sep 12, 2018 at 08:56:23AM +1200, Brian E Carpenter wrote:
>> On 2018-09-12 06:08, Robert Sparks wrote:
>>> I can live with this statement, but I don't like it.
>>>
>>> I'm in the camp that prefers the more specific "This changes the code 
>>> you need to write" camp - I would prefer Update be restricted to the 
>>> cases where you are changing the protocol defined in the updated 
>>> document in an essential way. 
>>
>> The IAB already opined indirectly on this topic.
>> https://tools.ietf.org/html/rfc6709#page-5 says:
>>
>>>>>    Extension designers should examine their design for the following
>>>>>    issues:
>>>>>
>>>>>    1.  Modifications or extensions to the underlying protocol.  An
>>>>>        extension document should be considered to update the underlying
>>>>>        protocol specification if an implementation of the underlying
>>>>>        protocol would need to be updated to accommodate the extension.
>>>>>        This should not be necessary if the underlying protocol was
>>>>>        designed with a modular interface.
>>
>> (followed by more detailed discussion).
>>
>> I'm not sure the IESG text is 100% compatible with this.
> 
> I believe it was intended to be, and I'm not sure what incompatibility you
> are seeing; could you say more?

There's a subtlety in this phrase:
  "would need to be updated to accommodate the extension."
Even though I'm a co-author of RFC6709, I'm not 100% sure what this means.
I think it means "if an implementor adds the extension to the code, she must
also modify the base code". The IAB text seems to be saying that if you add
a feature that does not *require* a change to the existing code, it's
not an update. I'm not sure I even agree with that, and I don't think
the IESG text does either. (If it does, we need a new tag "Extends:".)

>>> nor do they, by themselves, imply that implementers must implement the updating RFC to continue to comply with the updated one>>
>> seems to be going to far. It may be the intent of the update that
>> implementations *need* to be updated, because the update fixes a bug.
>> In that case, "updates" really means "partially obsoletes". 
> 
> Is there anything stopping the body text of the document from saying "this
> document updates [foo] by obsoleting the completely broken bits that do
> [bar]"?
> 
> Namely, the *keyword* does not indicate that you must update
> implementations.  The body text can try really hard to say that you should
> do so, though.

Yes.

    Brian
> 
> -Ben
>