[timeDomain: model for Time series] discussion on Timeseries Data model Note / how are ND-Cube DM and Timeseries DM connected ?

[Mireille Louys]

Dear DM and Time Domain followers,

I am trying, together with my CDS colleagues,  to recap on the various 
DMs available in the IVOA and understand the possible links between the 
future Time Series Model ( as sketched in Jiris's Note) and existing DMs 
like ND-Cube and STC 2.

Here is a graph proposed by Laurent Michel to clarify the links in 3 
main parts :

  * /DataSetMetadata DM/, which has the main ObsDataset Class ,
  * /ND-CubeDM/, which defines a SparseCubedataset
  * /TimeSerieCubeDM/, which highlights the special properties of a Cube
    depending on a Time axis

I think this is essential to highlight the inheritance path between 
these 3 DM building blocks:
a TimeSeriesCube  <is a >  NDCubeDM::SparseCubeDataset
a NDCubeDM::SparseCubeDataset <is a > DatasetMetadaDM::ObsDataset

ObsDataset has a /dataproduct//_//type/ attribute which allows to 
discover all dataproducts of type ' timeseries'.
this provides the container object for time-dependent data.

If we need to select /timeseries dataproducts/ according to some 
properties extracted from their data we can:
  - reuse what Obscore DM provides to explain general axes properties
target_name, s_region, s_resol, t_min, t_max, t_resol, em_min, em_max, 
em_resol, etc. are the basic properties for discovery

- provide a richer description of the TimeAxis and ObservableAxis.
For that , extracting  a statistical profile from the data contained in 
the Cube could do the job.
this means to access and analyse the Data part in ND-Cube , i. e the 
ND-Points gathered in a SparseCube Object

I guess more properties can be exposed to qualify the axes present in 
the Timeseries dataset , but for the moment , I see some overlap of 
notions between
CharacterisationDM::ObservableAxis,  STC2.0::CoordMeasurement (??) and 
TimeSerieCubeDM::CubeAxis.

This would be great if we could sort this out,
but currently , I would appreciate your feedback on the attached diagram 
, in order to proceed on the data model structure.

Cheers, Mireille ( after discussions together with Laurent, François, Ada)

-- 
--
Mireille Louys
CDS  						Laboratoire Icube
Observatoire de Strasbourg	Telecom Physique Strasbourg
11 rue de l'Université 		300, Bd Sebastien Brandt CS 10413 		
F- 67000-STRASBOURG			F-67412 ILLKIRCH Cedex
tel: +33 3 68 85 24 34

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