All,
I'm glad we are discussing this topic, but the fact that large data
providers are already distributing data using groups and hierarchies
is not a compelling reason to endorse this practice through CF. After
all, a lot of data providers are currently distributing scientific
data in any number of forms, and the point of CF (along with OGC
standards) is to help clean up the mess!
I agree that groups make sense for metadata and for certain types of
datasets. For example, the discrete sampling geometry featureTypes
like profile collection would be easier to understand and deal with as
a netcdf4 group of profiles rather than as a netcdf3 ragged array.
But the choice was made for CF 1.6 that backward compatibility was
more important.
I don't think it's cowardly to belive that the more folks use groups
to organize their data in an ad hoc way (the suitcase analogy), the
more it will hinder the remarkable progress that has been made
recently on finding and utilizing distributed CF data via the catalog
services (e.g. the geonetwork, gi-cat, geoportal, CKAN instances) that
many governments are setting up. When we open the data service
endpoints that our query returns, we need to have known data
structures, and that's what the CF featureTypes provide.
To return to the suitcase/clothing analogy again, we are rapidly
gaining the capability via good metadata and catalog services to find
all the black socks owned by Jim and Martin that have been washed in
the last week. But if our catalog query returns fourteen of Jim's
suitcases and twelve of Martin's, then we have more work to do.
Unlike socks, luckily we don't need actual suitcases to organize data,
we can construct collections on the fly using whatever attributes we
desire.
I would hope that our job as the CF community would be to identify
compelling additional specific featureTypes that we should support.
And if these identified featureTypes demand groups for efficiency or
some other reason, well, let's have that discussion.
-Rich
On Wed, Sep 18, 2013 at 12:08 AM, Roy Mendelssohn - NOAA Federal
<roy.mendelssohn at noaa.gov> wrote:
> Hi All:
>
> I am old and slow, and I must be missing something, because at this point most of the discussion has been about the desirability of files with groups and hierarchies. Again, unless I am missing something, there already are data providers who are distributing data using groups and hierarchies, including at least one very large data provider, and they obviously feel that there is a benefit to such structures. I am not arguing whether they are right or wrong, just that is the reality.
>
> If we start from that premise, then the real questions for discussion are should there be conventions on how groups and hierarchies are used in netcdf4 and hdf5 files, so that a user or software provider will know what to expect, and the second question is if it is deemed desirable to have such conventions, is CF the proper place for them to be developed.
>
> My sense it that this is what the original proposers are after.
>
> -Roy
>
>
> **********************
> "The contents of this message do not reflect any position of the U.S. Government or NOAA."
> **********************
> Roy Mendelssohn
> Supervisory Operations Research Analyst
> NOAA/NMFS
> Environmental Research Division
> Southwest Fisheries Science Center
> 1352 Lighthouse Avenue
> Pacific Grove, CA 93950-2097
>
> e-mail: Roy.Mendelssohn at noaa.gov (Note new e-mail address)
> voice: (831)-648-9029
> fax: (831)-648-8440
> www: http://www.pfeg.noaa.gov/
>
> "Old age and treachery will overcome youth and skill."
> "From those who have been given much, much will be expected"
> "the arc of the moral universe is long, but it bends toward justice" -MLK Jr.
>
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--
Dr. Richard P. Signell (508) 457-2229
USGS, 384 Woods Hole Rd.
Woods Hole, MA 02543-1598
Received on Wed Sep 18 2013 - 05:52:09 BST
