Re: [core] Benjamin Kaduk's Discuss on draft-ietf-core-senml-data-ct-05: (with DISCUSS and COMMENT)

Carsten Bormann <cabo@tzi.org> Wed, 13 October 2021 18:00 UTC

Return-Path: <cabo@tzi.org>
X-Original-To: core@ietfa.amsl.com
Delivered-To: core@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id F23FC3A0B3E; Wed, 13 Oct 2021 11:00:22 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.9
X-Spam-Level:
X-Spam-Status: No, score=-1.9 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id IdUbfq1ZLVz5; Wed, 13 Oct 2021 11:00:16 -0700 (PDT)
Received: from gabriel-smtp.zfn.uni-bremen.de (gabriel-smtp.zfn.uni-bremen.de [IPv6:2001:638:708:32::15]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id ABB5C3A0A34; Wed, 13 Oct 2021 11:00:15 -0700 (PDT)
Received: from [192.168.217.118] (p5089a8ac.dip0.t-ipconnect.de [80.137.168.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by gabriel-smtp.zfn.uni-bremen.de (Postfix) with ESMTPSA id 4HV0gF6MWBz2xjd; Wed, 13 Oct 2021 20:00:09 +0200 (CEST)
Content-Type: text/plain; charset="utf-8"
Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.120.23.2.7\))
From: Carsten Bormann <cabo@tzi.org>
In-Reply-To: <20211012170220.GA4103@kduck.mit.edu>
Date: Wed, 13 Oct 2021 20:00:09 +0200
Cc: The IESG <iesg@ietf.org>, draft-ietf-core-senml-data-ct@ietf.org, core-chairs@ietf.org, core@ietf.org
X-Mao-Original-Outgoing-Id: 655840808.9414001-9d9f8de8008151fc292ff3b83232e95f
Content-Transfer-Encoding: quoted-printable
Message-Id: <D53EDCDB-B113-4560-854A-F92386A21ABD@tzi.org>
References: <163233240502.20840.5498014177264082102@ietfa.amsl.com> <CC1B2304-A1F0-4E40-A4D1-CE7C1242FAA3@tzi.org> <20211012170220.GA4103@kduck.mit.edu>
To: Benjamin Kaduk <kaduk@MIT.EDU>
X-Mailer: Apple Mail (2.3608.120.23.2.7)
Archived-At: <https://mailarchive.ietf.org/arch/msg/core/vlFwD-wquu65ZiRlBKeSfK-JQaM>
Subject: Re: [core] Benjamin Kaduk's Discuss on draft-ietf-core-senml-data-ct-05: (with DISCUSS and COMMENT)
X-BeenThere: core@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Constrained RESTful Environments \(CoRE\) Working Group list" <core.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/core>, <mailto:core-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/core/>
List-Post: <mailto:core@ietf.org>
List-Help: <mailto:core-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/core>, <mailto:core-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 13 Oct 2021 18:00:23 -0000

Good morning Ben,

here are some answers to the remaining points on data-ct before we submit -06:

>>> (2) Let's also discuss whether we want to reuse ABNF rule names from
>>> HTTP while having the rule content diverge, without specific enumeration
>>> of the divergence.  So far I found instances where this document does
>>> not allow HTAB or obs-text in places that draft-ietf-httpbis-semantics
>>> does, which may well be the right way to spell the rule, but seems to
>>> merit a little discussion.
>> 
>> Very good point.  I’m not sure the ABNF behind “ABNF rule names from HTTP” is stable enough that we need to stick with it in all cases.
>> I was certainly surprised by the recent change to
>> 
>>   parameters = *( OWS ";" OWS [ parameter ] )
>> 
>> (which makes sequences of ";" legal; see also section B.2 in -semantics.) and wonder whether we should follow this change (and why!?).
> 
> I confess I looked at both 7230+7231 and the new -semantics while reviewing
> this doc, and didn't make a careful distinction between the two sources.

We actually decided to move entirely from 7230/7231 to httpbis-semantics, hoping that doesn’t put us in missref limbo forever.

In the interim meeting today, we agreed that the parameter optionality is among the legacy features (with HTAB and obs-text), so we left it out (and extended the comment in the ABNF what was left out.

All the changes mentioned in this mail are in:
https://github.com/core-wg/senml-data-ct/pull/10

[…]
>> The other difference from RFC 2616 and its descendants is the absence of “quoted-pair” from the “quoted-string” production, which indeed can be discussed.
>> 
>> (May need to discuss this in the interim tomorrow for final resolution.)

We agreed to restore quoted-pair (the bug fix I alluded to, over in httpbis), so we are (sans legacy) fully compatible with HTTP’s use of media types/content types.

[…]
>>> ----------------------------------------------------------------------
>>> COMMENT:
>>> ----------------------------------------------------------------------
>>> 
>>> Do we want to comment anywhere about the situation where an
>>> implementation receives a message using an IANA-registered numeric
>>> content-format that is "too new" for that implementation to know about?
>> 
>> (Should have a discussion about error handling in the interim tomorrow.
>> But generally, the important thing is that the implementation *know* that it needs to be updated to understand.)
> 
> True.

We wrote a new section “evolution”, which also answers the questions that Roman Danyliw did not ask :-)

We can’t really address the issue of SenML interoperability in this document providing a single definition of a pair of fields, so we expect there will be another draft (maybe also with other usage guidelines that improve that interoperability).

[…]

>>> Section 2
>>> 
>>>  Content-Coding:  A name registered in the HTTP Content Coding
>>>     registry [IANA.http-parameters] as specified by Section 8.5 of
>>>     [RFC7230], indicating an encoding transformation with semantics
>>>     further specified in Section 3.1.2.1 of [RFC7231].  [...]
>>> 
>>> (I expect that the RFC Editor will be able to replace the references to
>>> point to draft-ietf-httpb-semantics if it has been published before this
>>> document.)
>> 
>> (With the actual changes in this document, I’m not sure that is a mechanical operation. But let’s wait for httpbis-semantics to emerge from EDIT.)

Definitely not mechanical, but easy enough (but subject to change due to EDIT).

We plan to merge PR 10 soon and submit a new I-D.

Grüße, Carsten