DM Workshop wrap-up

Wed Jul 21 17:39:15 CEST 2021

Hell all, 

This would be a very clean solution.

- Gerard proposed to rephrase the XSD in order to isolate complexTypes from elements which should make easier the validation in the context of a VOTable.
- We have been using XSD1.1 (with Python) because the merged syntax put many constraints on element attributes. This is a key point of the proposal. I do not think that such rules could be set with XSD1.0
  - The xerces web site does not look worry about this (https://xerces.apache.org/xerces2-j/faq-xs.html <https://xerces.apache.org/xerces2-j/faq-xs.html>) but I’ve no experience with this code
  - I’ve no idea about how could this fit with volint either. 

Best
Laurent 

> On 21 Jul 2021, at 17:02, Mark Taylor <m.b.taylor at bristol.ac.uk> wrote:
> 
> François,
> 
> Yes, I think that use of the xs:any type is the right way to go here.
> 
> However, that is already accommodated by the VOTable schema as it stands.
> Quoting from https://www.ivoa.net/xml/VOTable/VOTable-1.4.xsd: <https://www.ivoa.net/xml/VOTable/VOTable-1.4.xsd:>
> 
>  <xs:complexType name="Resource">
>    ...
>      <!-- Suggested Doug Tody, to include new RESOURCE types -->
>      <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
>    ...
>  </xs:complexType>
> 
> which means that the elements from the VODML schema can be included
> within a RESOURCE element in a VOTable document, with no changes
> to the VOTable standard required at all (thanks to Markus for
> pointing this out).
> So something like this should work out of the box:
> 
>  <VOTABLE version="1.4"
>           xmlns="http://www.ivoa.net/xml/VOTable/v1.3 <http://www.ivoa.net/xml/VOTable/v1.3>"
>           xmlns:dm="http://www.ivoa.net/xml/vodml <http://www.ivoa.net/xml/vodml>">
>    <RESOURCE type="meta">
>      <dm:VODML ...>
>        <MODELS>
>        </MODELS>
>        ...
>      </dm:VODML>
>    </RESOURCE>
>    <RESOURCE type="results">
>      <TABLE>
>        ...
>      </TABLE>
>    </RESOURCE>
>  </VOTABLE>
> 
> A VOTable document like that validates for me under the VOTable 1.4
> schema (e.g. xmllint -noout -schema VOTable1.4.xsd).  At present votlint
> (http://www.starlink.ac.uk/stilts/sun256/votlint.html <http://www.starlink.ac.uk/stilts/sun256/votlint.html>) does complain:
> 
>   WARNING: Element in wrong namespace (http://www.ivoa.net/xml/vodml <http://www.ivoa.net/xml/vodml> not http://www.ivoa.net/xml/VOTable/v1.3 <http://www.ivoa.net/xml/VOTable/v1.3>)
> 
> but that's really a votlint bug that I will fix.
> 
> I would certainly favour this approach rather than adding new VOTable
> elements, to avoid unnecessary coupling between the VODML and VOTable
> standards.
> 
> Concerning the xsi:type="mapping:VODML-type" attribute:
> as I understand it, that wouldn't work with a schema in the form
> of the one at
> 
>   https://github.com/ivoa-std/ModelInstanceInVot/blob/master/schema/xsd/merged-syntax.xsd <https://github.com/ivoa-std/ModelInstanceInVot/blob/master/schema/xsd/merged-syntax.xsd>
> 
> since that defines elements directly and not types (Gerard queried
> this stylistic decision during the DM workshop session #4).
> 
> So I'm not quite sure how validation of the embedded VODML would
> proceed: either the schema could be rephrased to define types, or
> perhaps XSD validators are able to determine the required contents
> based on the <VODML> element name without requiring an xsi:type.
> 
> One other point on the current merged-syntax.xsd: use of XMLSchema 1.1,
> instead of 1.0, makes it harder to validate using some tools.
> Java support at least is not so good for XSD 1.1, so I don't know
> whether votlint would be able to provide XSD validation for VODML
> if it was defined using this schema.
> 
> Mark
> 
> 
> 
> On Fri, 16 Jul 2021, BONNAREL FRANCOIS wrote:
> 
>> Hi all,
>>     Considering the VOTAble schema versioning issue, with the "import" of a
>> mapping syntax which may evoluate on its own I wonder i something like the
>> following could work.
>>     1 ) in next VOTABLE schema version, create a "VODML" tag inside VOTable of
>> type "anyType" (minoccurs = 0 of course)
>>     2 ) in VOTABLE documents type this VODML tag with an
>> xsi:type="mapping:VODML-type" , with "mapping" xmlns defined as the last
>> version of the mapping xml schema (can be done with attributes of the VODML
>> tag)
>>     3 ) as far as I remember this would make the two schemata independant and
>> does not require that VOTABLE documents import the mapping schema
>> 
>> Do you think it could work ?
>> 
>> Cheers
>> François
>> 
>> Le 15/07/2021 à 11:36, Laurent Michel a écrit :
>>> Dear DM,
>>> 
>>> Last Tuesday we had our last DM workshop meeting.
>>> This concluded a fruitful 7-month process whose main conclusions and
>>> prospects are listed below.
>>> 
>>> An overview of the work done has been presented by LM
>>> (https://wiki.ivoa.net/internal/IVOA/Dm2021/MAY2021-ws41.pdf
>>> <https://wiki.ivoa.net/internal/IVOA/Dm2021/MAY2021-ws41.pdf <https://wiki.ivoa.net/internal/IVOA/Dm2021/MAY2021-ws41.pdf>>)
>>> 
>>> Conclusions in short
>>> ================
>>> 
>>> • Models:
>>> • Meas, Coord, PhotDM, Dataset, Cube and MANGO accepted
>>> • New use-cases to be investigated
>>> • X-RAY Astronomy
>>> • Asteroids, multi-core datasets
>>> • CTA and MM astronomy : meta-data characterization
>>> 
>>> • Data Provider / client specific use-cases
>>> • Need for annotations to help processing spectra
>>> • Need to associate parameters
>>> • Need for a simple description of the photometric calibration
>>> • Need for a simple view on Provenance
>>> • Annotation on the fly feasible
>>> • Model-based PyVO API easy to design
>>> 
>>> • Mapping syntax
>>> • Divergence between the 2 proposals (VODML mapping and ModelInstanceInVot)
>>> • Proof of concept for a YAML serialization of model instances
>>> 
>>> Annotation
>>> =========
>>> An important effort has been made over the last 6 weeks to merge the 2
>>> syntax proposals:
>>> • see on https://github.com/ivoa-std/ModelInstanceInVot <https://github.com/ivoa-std/ModelInstanceInVot>
>>> <https://github.com/ivoa-std/ModelInstanceInVot <https://github.com/ivoa-std/ModelInstanceInVot>>
>>> 
>>> • 3 items available so far:
>> 
>> 
>> 
> 
> --
> Mark Taylor  Astronomical Programmer  Physics, Bristol University, UK
> m.b.taylor at bristol.ac.uk <mailto:m.b.taylor at bristol.ac.uk>          http://www.star.bristol.ac.uk/~mbt/ <http://www.star.bristol.ac.uk/~mbt/>
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