Draft note on STC in the Registry

[Pierre Fernique]

Hi all,

First of all, thanks Markus for this note 
(http://docs.g-vo.org/regstcnote.pdf). On my point of view it is a 
pragmatic approach of coverage manipulation challenge which has a good 
chance to be implemented and used. I agree for most of the suggestions. 
I just highlight these points :

 1. *"double precision"* : Our experience on MOCs has shown us that the
    coverage is never enough accurate for the users. The approach to
    have two levels of precision - a low precision coverage inside
    registry, and  possibly a high one outside via URL -  is certainly a
    very good thing.
    My question : I imagine that we could have the same need for time
    coverage, and may be for energy coverage. See point 5
 2. *T**able or catalog coverage ?* Presently, the "FOOTPRINT" element
    (cf end of the section 2.2) is dedicated to the global resource. The
    problem: for catalogs containing several tables it is actually not
    possible to know each individual table coverage. I would suggest
    that this IVOA note will propose something to fix this issue.
 3. *MOC frame* (related to section 4.1-b) IVOA provides now several
    data collection (tables or HiPS) dedicated to planets. In the case
    of HiPS, we have had already to introduce new reference coordinate
    system as a list of planet names (hips_frame=mercury, venus, moon,
    mars, mimas, etc...). This solution works fine for HiPS, but as a
    HiPS is distributed with its associated MOC, it means that these
    associated MOCs are not celestial, but planet dependent. It could be
    a good thing if we use the same controlled vocabulary for HiPS, MOCs
    and registry.
 4. *MOC ASCII* => see my previous mail concerning the MOC ASCII
    serialization.

 5. *Temporal MOC*. We are starting to explore the idea of a temporal
    MOC. In one word - but probably more at the next IVOA meeting - it
    would be the same logic of a spatial MOC but for time based, not
    HEALPix dependent, but based on a fix reference time system and unit
    (JD - barycenter - in fact identical to 2.1 definition). Having a
    list of MJD ranges as internal registry coverage will immediately
    allow us to build corresponding "TMOC" (and may be later and
    extension of the MOCserver also time oriented). So I would applause
    the usage of collections of MJD ranges for describing time coverage.

Cheers
Pierre

Le 17/01/2018 à 10:58, Markus Demleitner a écrit :
> Dear colleagues,
>
> Those who attended our session in Shanghai may remember my talk on
> how we can finally get proper STC queries against the Registry --
> http://wiki.ivoa.net/internal/IVOA/InterOpMay2017-Reg/reg-stc.pdf
>
> I've finally done the various implementation parts to try everything
> out in DaCHS and the relational registry (at this point, it's only on
> the Heidelberg mirror, since harvesting the MOCs is quite a bit of
> pain).
>
> Based on that experience, I'd now propose a roadmap for how we could
> move towards more-or-less universal declaration of coverages in
> space, time, and spectrum for the VO Registry.  I've drafted
> a Note that I'd like to upload to the document repository -- probably
> some time next week unless you want more time for discussions.
>
> A draft of the note is available from
> http://docs.g-vo.org/regstcnote.pdf, the sources (that you're welcome
> to work on) are in volute at
> https://volute.g-vo.org/svn/trunk/projects/registry/regstcnote
> -- this includes a copy of the modified VODataService schema that
> will later be part of the upload.
>
> After this, I'd be grateful if you (yes, you!) could
>
> (a) briefly review the thing to and protest quickly if you strongly
> disagree with the main points of the note?  Ideally, I'd like the
> note to represent the "rough consensus" that's traditionally half of
> the RFC process (the other part being "running code").
>
> (b) perhaps look a bit deeper at the stuff if you're interested a bit
> more in the registry/STC borderline.  If you still feel comfortable
> with the note then, I'd be happy to include you on the author list.
> I feel a bit odd being the only author on something fairly
> wide-reaching, and certainly some of you out there had important
> roles in shaping what's written there during the past six years or so
> (yeah: according to RegTAP WD-20121112, it removed a first version of
> this...).  So: If you can see your name on this note, just drop me a
> note, and don't be shy or overly modest.
>
> Thanks,
>
>              Markus


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