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gilleslandais edited this page Mar 25, 2021 · 17 revisions

Mango proposal

Mark CD comments

Models

  • Mango:
    • I've sumbitted Issues to the Mango repository with comments/suggestions on the model.
    • Parameter.description: is this a modeled concept?
      • there is some question (in my mind anyway) on whether something like this is a modeled concept (ie: an attribute on an object), since it can apply to any object, is completely arbitrary, often not included, and in no way contributes to the definition of the object itself.
      • the alternative is to not included it in the Model element(s), but let the Annotation address it in some way.
        "Any object may have a description. If supported by the implementation, the value is pulled from the VOTable DESCRIPTION sub-node of the associated PARAM|FIELD|TABLE" (we don't annotate GROUPs I think).

Annotations

  • Annotating content within a VOTable element (PARAM, FIELD, etc)
    This came up in the context of mango:Param.description where, if this is a modeled element, we may want to populate it from the VOTable content. However, the VOTable DESCRIPTION element cannot be referenced, it is internal to other VOTable elements (PARAM, FIELD, GROUP, TABLE).
    • The annotation syntax Laurent uses (Vodml-instance-vot) has elements (SC_*) which are supposed to handle this sort of problem.
      • Section 3.12 describes these "shortcuts"
        • example case (Quantity) illustrates annotating an ivoa:Quantity using this syntax.
          • uses independent ATTRIBUTEs for the Quantity.value and Quantity.unit
        • The SC_*QUANTITY tags consolidate this grouping into a single annotation tag.
        • Question: is there no way to assign a Quantity.unit from the 'unit' arg of PARAM|FIELD?
      • given the description in Section 3.12, I do not see how it satisfies this case of annotating content within a VOTable element atom.

LM answers

MANGO

  • Although all use-cases are supported by Mango, some weakness have been pointed out. They have been issued on the MANGO pages and will be subject to a major PR after the workshop.

Annotations

  • unit element shouldn't be mandatory in SC*QUANTITY. This part of the spec must be enhanced.

GL - VizieR mango experiments (and proposal)

a beta-prototype has been implemented to provide rich VOTable using Mango:

http://viz-beta.u-strasbg.fr/viz-bin/Mango? [vizier-asu-parameters]

e.g.:

The beta-prototype is available for vizier queries having a unique table in output.

The capabilities implemented are:

  • measure annotation available (currently) for positions, photometry, parallax
  • associated data is used to link the VizieR catalogue Provenance
  • grouping column mechanism to gather columns related to a same measure

The beta version is a piped process which takes a VizieR VOTable in input, extracts metadata from the VOTable (COOSYS and FIELDS definition) and returns in output a VOTable enriched with a VODML(lite) section header. The process is completed with a VizieR database connection to extract some metadata not available in the VOTable (v1.4) like the photometry systems.

Measure annotation

Important: filters are not (always) in the original article but assigned by CDS.

Provenance

Provenance is important for end-users to be aware of the data origin. There are indeed no standard way today to annotate authors, articles, year of publications in a VOTable. Furthermore, the VizieR process can assign metadata (like photometry) which is not part of original data. This information is described in a beta implementation of ProvDM.

In the VizieR Mango prototype, the provenance is added as an associated data with URLs (e.g.: http://viz-beta.u-strasbg.fr/viz-bin/Mango?-out.max=10&-source=J/ApJ/789/115 - see collection with dmrole="mango:Source.associatedDataDock")

Grouping columns

Mango enables to gather measures with errors. But the "associatedParameters" anables also to group columns related to a same measure. For instance a quality flag which qualifies the measure given in an other column.

e.g.: catalogue J/A+A/584/A5 (Evans, 2015)

The table “table2” contains 2 radial velocity columns: RV1 (primary velocity) and RV2 (secondary velocity). Each of theses columns are qualified with an error and a number of observation used to compute the radial velocity measure. So we can gather columns: (RV1, e_RV1, o_RV1) and (RV2, e_RV2, o_RV2)

Examples:

Please put your name or initials in the front of your constributions (see the guide)

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