Cube/ImageDM - Comments on Observation-Dataset Overview diagram

[Robert J. Hanisch]

Hi Arnold et al.,

I don't think there is any universal agreement on the definitions of data set, dataset, data product, data file, etc.

FWIW, Wikipedia says a dataset "corresponds to the contents of a single database table."  "The term dataset may also be used more loosely to refer to the data in a collection of closely related tables, corresponding to a particular experiment or event."

In space physics, individual files are called "granules" (http://www.spase-group.org/school/tutorials/data/#granule ).

I would think the most important thing would be to define "dataset" clearly in the current context.

Bob

From: Arnold Rots <arots at cfa.harvard.edu<mailto:arots at cfa.harvard.edu>>
Date: Tuesday, 13 May 2014 11:35 AM
To: "CresitelloDittmar, Mark" <mdittmar at cfa.harvard.edu<mailto:mdittmar at cfa.harvard.edu>>
Cc: Data Models mailing list <dm at ivoa.net<mailto:dm at ivoa.net>>
Subject: Re: Cube/ImageDM - Comments on Observation-Dataset Overview diagram

Then I agree with Pat's approach.
"Dataset" is very misleading if it is to refer to a single file.
That, indeed, is a DataProduct and the name ought to be changed.

That said, though, you may want to consider whether all possible
data products are covered by the derived classes. The parent class
may still be needed to be used as a generic type for unclassified
data products.

  - Arnold

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Arnold H. Rots                                          Chandra X-ray Science Center
Smithsonian Astrophysical Observatory                   tel:  +1 617 496 7701
60 Garden Street, MS 67                                      fax:  +1 617 495 7356
Cambridge, MA 02138                                         arots at cfa.harvard.edu<mailto:arots at cfa.harvard.edu>
USA                                                   http://hea-www.harvard.edu/~arots/
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On Tue, May 13, 2014 at 10:50 AM, CresitelloDittmar, Mark <mdittmar at cfa.harvard.edu<mailto:mdittmar at cfa.harvard.edu>> wrote:

Arnold,


On Tue, May 13, 2014 at 10:03 AM, Arnold Rots <arots at cfa.harvard.edu<mailto:arots at cfa.harvard.edu>> wrote:



Because I don't think ObsDataset is something anyone would instantiate..
It must be some "kind" of dataset to be useful,  an ImageDataset, SpectralDataset, or even for
the DAL services, the particular QueryResponse.

I'm not so sure. An ObsDataset could be a collection of ImageDataset, SpectralDataset, etc.
Close to home: the Chandra data distribution tar files are really ObsDatatsets and contain
images, spectra, sparse cubes, etc.

  - Arnold


This is why it will be important to be very specific about what we mean by "Dataset".
 In these diagrams, I am interpreting it as 'a result', a single file if you will. The
'tar' ball would be a collection of different flavors of <ObsDataset>.

There has been some discussion on this earlier.  I think it was Pat, who mentioned that he
has switched to using the term "DataProduct" for a single 'result' file, because it is less
ambiguous.  However, since Dataset was already in use for these models, I kept the names.

Mark



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