[Standards] Exact hint for Result Set Management

Dave Cridland dave at cridland.net
Thu Jul 12 14:12:01 UTC 2018


On 12 July 2018 at 12:24, Florian Schmaus <flo at geekplace.eu> wrote:

> On 12.07.2018 12:39, Kevin Smith wrote:
> > On 12 Jul 2018, at 11:23, Matthew Wild <mwild1 at gmail.com> wrote:
> >>
> >> On 11 July 2018 at 18:25, Florian Schmaus <flo at geekplace.eu> wrote:
> >>> On 11.07.2018 18:01, Matthew Wild wrote:
> >>>> On 11 July 2018 at 16:33, Florian Schmaus <flo at geekplace.eu> wrote:
> >>>>> I recently submitted PR #672 to the xeps repo
> >>>>>
> >>>>> https://github.com/xsf/xeps/pull/672
> >>>>>
> >>>>> to make users of RSM, like MAM, aware whether the result is exact or
> >>>>> not. It received some scepticism from the council members in today's
> >>>>> council meeting. I am to blame here as I thought the abstract
> motivation
> >>>>> in the commit message was enough. It appears it wasn't.
> >>>>>
> >>>>> While I think multiple applications could exploit that information,
> my
> >>>>> particular motivation was MAM. Consider the scenario where you have a
> >>>>> master archive and a local archive. The local archive may have
> multiple
> >>>>> holes at unknown locations. Now you want to sync your local archive
> from
> >>>>> the master using MAM/RSM.
> >>>>
> >>>> I'm not keen on this solution for the premise you've given.
> >>>>
> >>>> I don't believe that when using MAM correctly you would ever end up
> >>>> with "holes at unknown locations" in your local archive. I don't think
> >>>> that encouraging people to use a "bisection algorithm" is the right
> >>>> thing to do.
> >>>
> >>> So you don't want MAM users to be able to efficiently sync archives
> with
> >>> multiple holes by a simple change because you do not want MAM to be
> used
> >>> in scenarios where this could happen?
> >>
> >> Just adding this flag will not make servers implement it, so it's
> >> going to add code and still need a fallback.
> >
> > And, as specified (optional but with no default or meaning for a missing
> flag) it seems unhelpful
>
> As Georg mentioned yesterday, the default is exact="maybe". There is
> also a sentence explaining the semantic of the missing hint:
>
> https://github.com/xsf/xeps/pull/672/files#diff-
> fd691aeb84210578723b940e9881ab7eR200
>
> > and as it adds a SHOULD, in a Draft XEP, with no namespace bump or
> > discovery, it’s adding ambiguity and confusion..
>
> I don't think that this is true, but we certainly can talk about making
> it just a recommendation if it is a blocker.
>
>
There's no difference.

>From RFC 2119:

3. SHOULD   This word, or the adjective "RECOMMENDED", mean that there
   may exist valid reasons in particular circumstances to ignore a
   particular item, but the full implications must be understood and
   carefully weighed before choosing a different course.



> - Florian
>
>
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