Re: [Sedate] Distinguishing "optional extra" vs "you need to understand this to process the date accurately" extensions
Justin Grant <justingrant.ietf.public@gmail.com> Thu, 09 December 2021 19:56 UTC
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From: Justin Grant <justingrant.ietf.public@gmail.com>
Date: Thu, 09 Dec 2021 11:55:50 -0800
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To: john-ietf@jck.com
Cc: Carsten Bormann <cabo@tzi.org>, Bron Gondwana <brong@fastmailteam.com>, sedate@ietf.org
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Subject: Re: [Sedate] Distinguishing "optional extra" vs "you need to understand this to process the date accurately" extensions
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For the core timestamp format (from RFC 3339) and for time zone annotations (which already exist in java.time and similar libraries like Noda Time for .NET), adding a "this is required" character would break backwards compatibility. I'd be somewhat concerned about formats like 2022-12-19T16:39:57!-08:00[!America/Los_Angeles] for that reason. For new extensions like calendar without prior art, it seems more reasonable to have an indicator of what's required vs optional. That said, I'd be concerned that senders might not have a clear understanding of what the receiver is going to do with the data-- so the sender may have to guess about whether to include the "!" or not. Or in the case of storing strings in a database, the sender might not know who's going to be using that data in the future, and for what purpose. In that case, the sender won't really know whether to include the "!". Unless we can define a really clear, deterministic way for senders to know whether to include the "!" or not, then I worry that we'd end up with a somewhat-random patchwork of usage where some senders add the "!" and some don't for the same use case. Best, Justin On Thu, Dec 9, 2021 at 8:06 AM John C Klensin <john-ietf@jck.com> wrote: > > > --On Thursday, December 9, 2021 15:59 +0100 Carsten Bormann > <cabo@tzi.org> wrote: > > > On 2021-12-09, at 14:04, Bron Gondwana > > <brong@fastmailteam.com> wrote: > >> > >> So I wonder if we need a syntax to say "if this extension is > >> not recognized by the receiving system, it SHOULD throw an > >> error and MUST NOT expect the date to be exact" - either a > >> reserved namespace for such extensions, or some other > >> syntactical sugar. > > > > Protocols typically have a way to distinguish "critical" > > (or "must-understand") options from "elective" > > options. Sometimes, the distinction is baked into the option > > code, sometimes there is separate place (which also allows the > > same option to be used in both ways). Our syntax should > > provide an easy way to do the latter, as in: > > > > 1996-12-19T16:39:57-08:00[America/Los_Angeles][u-ca=hebrew] > > (Elective, ignore option if not understood) > > > > 1996-12-19T16:39:57-08:00[America/Los_Angeles][u-ca!hebrew] > > (Critical, must understand/must reject date if not understood) > > > > Well, we need better examples... > > Carsten, > > Using your examples and adapting your syntax (purely as > examples), would you also expect/allow > > 1996-12-19T16:39:57-08:00[!America/Los_Angeles][u-ca=hebrew] > How about > > 2022-12-19T16:39:57!-08:00[!America/Los_Angeles][!u-ca=hebrew] > which might mean "that time, somewhere"? > > :-( > Standing one the edge and looking down the slippery slope here. > > best, > john > > > -- > Sedate mailing list > Sedate@ietf.org > https://www.ietf.org/mailman/listinfo/sedate >
- [Sedate] Distinguishing "optional extra" vs "you … Bron Gondwana
- Re: [Sedate] Distinguishing "optional extra" vs "… Carsten Bormann
- Re: [Sedate] Distinguishing "optional extra" vs "… John C Klensin
- Re: [Sedate] Distinguishing "optional extra" vs "… Justin Grant
- Re: [Sedate] Distinguishing "optional extra" vs "… Bron Gondwana
- Re: [Sedate] Distinguishing "optional extra" vs "… John C Klensin