Error in the WD-STC-S-1.0-20130918 document?

CresitelloDittmar, Mark mdittmar at cfa.harvard.edu
Fri Dec 8 18:11:45 CET 2023 

All,

> Should an erratum be issued?
I agree with Markus on this.  The STC-S document was originally a Note, and
now a WD.. in either case, there should be no expectation for stability and
nothing on which to file an erratum.

> Do Coords and Meas offer an ASCII-String serialization? (Laurent?)
   STC-S is a serialization standard which was designed to map to the
STC-1.33 model.
   It can, in principle, be mapped to other models as well.  So one could
use the same syntax to identify elements from the "STC2" replacement models.
   However,
       1) I'm not sure if the content of Meas/Coords covers everything the
syntax mapped to since their scope was required to be as minimal as
possible.
             (e.g. Redshift, is not in the current Meas model).
       2) Meas, Coords and Transform models only cover some of the
components from the original STC scope.  Regions, Intervals, and Areas are
not covered
           and are a big part of the STC-S syntax.

> Let's move that WD to the "Obsolete IVOA documents"
Taking Francois' list another step, a quick scan of how those RECs relate
to STC-S.

   - STC-S: Space-Time Coordinate Metadata Linear String Implementation
   (DAL-WD-20130917)
   - replaces earlier IVOA-Note by Arnold Rots (20091030)
   - TAP-1.0: Section 6, “Use of STC-S in TAP *(informative)*”
      - Recommends using THEIR interpretation of STC-S based on the 1.30
      STC-S NOTE, and STC DM 1.33 REC.
      - F-X notes that this differs from the STC-S WD
   - TAP-1.1:
      - Section 2.7.2 - on upload, DALI syntax MUST be supported, previous
      STC-S convention MAY be supported; strongly recommends output in
DALI syntax
         - this moves away from the STC-S representation in favor of DALI
         syntax.
      - The document doesn't even provide a reference for the STC-S syntax
      any more.
   - ADQL-2.0:
      - Section 2.4.1: Region function
         - “The format of the string is to be specified by a service that
         accepts ADQL by referring to a standard format.  Currently STC/s
         is the only standardized string representation a service can declare”
      - Section 2.4.14: REGION
         - “ The format of the string MUST be specified by a service that
         accepts ADQL by referring to a standard format.  Currently STC/s
         is the only standardized string representation a service can declare”.
      - Reference: http://www.ivoa.net/Documents/latest/STC-S.html
which resolves
      to https://www.ivoa.net/documents/Notes/STC-S/, the IVOA-Note by
      Arnold, v1.33 20091030
   - ADQL-2.1: REC 20230418
      - Section 3.5: supports DALI geometry types; and STC-S based regions
      as defined in the STC-S specification (Rots and Demeitner et al; 2013)
      - Section 4.7.1: Geometry:  DALI MUST be supported.. “Note that other
      specifications (e.g. STC/s) or any other kind of value MAY also be
      supported.”
      - The reference: http://ivoa.net/documents/STC-S/ resolves to the
      20130917 WD.

It appears that the IVOA is moving away from STC-S in favor of the DALI
syntax.
It seems like we need to preserve some stable instance of the WD since it
is referenced in RECs.  Can this be down-graded to an update of the Note?
This would provide an end-point for the existing references, but can also
stop work on that front so the focus can move to the DALI syntax.

Mark




On Fri, Dec 8, 2023 at 9:48 AM BONNAREL FRANCOIS <
francois.bonnarel at astro.unistra.fr> wrote:

> Dear all,
> Coming back to this after a week or so.
>
> What we have here could be an issue of backwards compatibility.
>
> - TAP 1.0 ( REC 2010) enhances stsc-s for spatial geometries (but we may
> need a spectral frame to define this probably)
> So does ADQL 2.0
> - ObsCore 1.1 (REC 2017) let open that future versions of TAP and ADQL may
> support the ObsCore table and queries in the future but still requires
> stc-s strings in s_region at the time of writing.
> I don't think we define clearly somewhere which of the DALI xtypes we can
> use in s_region if we are ported by new versions of TAP/ADQL
> TAP 1.1 was a  REC in 2019
> ADQL 2.1 : REC last month !!
>
> So my guess is that we have a lot of ObsTAP services (or ObsCore tables in
> TAP services) which still use stc-s extensively.
>
> Backwards compatibility would require that this still supported and not
> considered as an obsolete document.
>
> So to face FX issue some erratum should be written somewhere to explain
> the BNF had to be fixed. I don't know if this is to be done in TAP 1.0, in
> DALI or in ObsCore 1.1 itself
>
> Cheers
> François
>
> Le 30/11/2023 à 21:39, Adrian Damian a écrit :
>
> Hi F-X,
>
> I gave a presentation on this subject at the last IVOA interop. We at
> the CADC went through the same exercise with the parser just to discover
> that it has no future and we should direct effort elsewhere. Maybe a
> MOC-regions parser and encoder that could be then used for footprints?
>
> The bottom line is that STC-S leaves a void that we as a community need to
> fill in soon. So yes, I agree that STC-S should be moved to a retired
> documents corner but at the same time a replacement should be put in place.
> I'm not sure which WG should drive this.
>
> Adrian
>
> On Thu, Nov 30, 2023 at 8:55 AM Francois-Xavier PINEAU <
> francois-xavier.pineau at astro.unistra.fr> wrote:
>
>> Hi Markus,
>>
>> Thank you very much or your answer.
>>
>> I was not aware of your parser:
>> * what do you mean by 'halfway complete'?
>> * what about using it in astropy regions (
>> https://github.com/astropy/regions/issues/21) ?
>>
>> > Do you have a strong reason to do that? Several users have been asking
>> for MOC creation from a STC-S string, and we have been thinking to add this
>> features to MOC Lib Rust (and hence, to MOCPy). And: 1 - I was not aware of
>> the subset (for geometries) defined in the TAP document (again, thank
>> you); 2 - STC-S could be used as an input to create ST-MOCs, F-MOCs, ... in
>> addition to S-MOCs.
>>
>> There are others possibilities (STC-S based queries in QAT2S, more
>> general STC-S parser in Aladin Lite, ...).
>>
>> > The operationally (still) relevant subset for specifying geometries is
>> in section 6 of TAP 1.0
>> Grrr... I see that:
>> * the 'frame' is mandatory in the STC-S document and optional in TAP,
>> * the vocabulary is not exactly the same:
>>     CART[123] vs CARTESION[123]
>>     SPHER2 vs SPHERICAL2
>>     It 's easy to support both inputs, but an option is needed in output
>> (to choose between the STC note and the TAP standard).
>>
>> FWIW, I just published a first version of the Rust STC-S parser:
>> https://github.com/cds-astro/cds-stc-rust
>> For non-Rust users the main interest so far may be to transform STC-S
>> string into JSON, back and forth.
>>
>> > Let's move that WD to the "Obsolete IVOA documents" Since it has been
>> asked by users, it seems that STC-S is used, right? Do Coords and Meas
>> offer an ASCII-String serialization? (Laurent?) (Maybe I am old school,
>> but I kind of like ASCII-String serializations)
>>
>>
>> fx
>>
>>
>> Le 29/11/2023 à 11:09, Markus Demleitner a écrit :
>>
>> Hi FX,
>>
>> On Tue, Nov 28, 2023 at 04:58:34PM +0100, F.-X. Pineau wrote:
>>
>> I am implementing a STC-S parser (in Rust, obviously) from the
>> WD-STC-S-1.0-20130918 document:
>>
>> https://www.ivoa.net/documents/STC-S/20130917/WD-STC-S-1.0-20130917.html
>>
>> Do you have a strong reason to do that?  You see, I've once written a
>> halfway complete one (if you're interested:https://gitlab-p4n.aip.de/gavo/dachs/-/tree/main/gavo/stc), and I've
>> regretted it, as there is little use for it.
>>
>> The operationally (still) relevant subset for specifying geometries
>> is in section 6 of TAP 1.0<https://ivoa.net/documents/TAP/20100327/REC-TAP-1.0.html> <https://ivoa.net/documents/TAP/20100327/REC-TAP-1.0.html>.
>>
>> Even there, there's no formal specficiation, and really, nobody wants
>> to touch the whole mess; in our DALI discussions, there was zero
>> enthusiasm for moving that material into that spec (where it could
>> become normative).  See the current DALI 1.2 WD for the sort of types
>> we would like to use in the future.
>>
>> But, well, the TAP 1.0 STC-S subset at least is (still) in active
>> use.
>>
>>
>> Is the grammar wrong?
>> Is there an 'official/original' STC-S parser that could be used as a
>> reference?
>> Should an erratum be issued?
>>
>> The document is a (fairly rough) working draft, so there wouldn't be
>> an erratum but a new working draft.
>>
>> But nobody has touched the WD in a decade, and I don't see that
>> change, in particular since the underlying data model (STC 1.03) has
>> been superseded by Coords and Meas in the meantime.
>>
>> My take would be: Let's move that WD to the "Obsolete IVOA documents"
>> section in the doc repo.  It keeps confusing people who are actually
>> looking for the TAP 1.0 geometry specification.
>>
>>         -- Markus
>>
>>
>
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