[CF-metadata] thredds changing CF conventions version

From: Seth McGinnis <mcginnis>
Date: Wed, 28 Aug 2013 12:59:27 -0600

Hi Sean,

Personally, I would regard that as suspect behavior.

I'm of the opinion that it's best practice for a data service to
affect the data it operates on in very targeted and transparent
way, and that it should pass everything else through untouched.
If it doesn't do that, it's harder to trust the service, because
the more ways that it modifies the data, the more opportunities
there are for it to get something wrong, and the more likely it
is that the error will go unnoticed because it's hiding amongst a
bunch of other changes.

Case in point, I have recently discovered that when the THREDDS
server subsets CF data that uses a coordinate system other that
lat-lon, it mangles a bunch of the ancillary data in the file. I
suspect this happens, ironically enough, precisely because it's
trying to make the data CF-1.0 conformant instead of just leaving
it as-is...

So yes, I think it's significant that the data coming out of
THREDDS is in a different convention than the source files, and
that it's cause for concern.

Cheers,

--Seth

----
Seth McGinnis
NARCCAP Data Manager
NCAR - IMAGe
On Wed, 28 Aug 2013 10:11:10 -0700
 John Graybeal <john.graybeal at marinexplore.com> wrote:
>It isn't just about feature presentation, right?  On the assumption that the
>latest version is always most current (so everyone will use the latest version
>if they can), I use the version as a proxy for how
>current/up-to-date/sophisticated the data provider is.  
>
>It also gives me a clue about which standard name table version they might
>use, though that version info is often available elsewhere.
>
>If true, this may help explain why so few data providers seemed to be using
>1.6, anyway....
>
>John
>
>On Aug 28, 2013, at 08:56, John Caron <caron at unidata.ucar.edu> wrote:
>
>> Hi Sean:
>> 
>> What feature of CF are you using that you need to preserve the version?
>> 
>> John
>> 
>> "If you torture data long enough, it will confess."
>>  -- Economist Ronald Coase
>> 
>> 
>> 
>> On 8/28/2013 3:28 AM, Gaffney, Sean P. wrote:
>>> Hi,
>>> Here at the British Oceanographic Data Centre we use THREDDS to deliver
>>> and subset our numerical model data that we hold in CF netcdf format.
>>> I?ve just been made aware that during the delivery and subsetting
>>> process, THREDDS seems to be converting the CF files we hold from
>>> whatever CF convention they have been supplied in, to CF 1.0.
>>> Is this something that the rest of the community are aware of, and if
>>> so, do people consider it to be of major importance that the files
>>> outputted by thredds are in a different convention to the source files
>>> thredds interrogates?
>>> Cheers
>>> Sean Gaffney
>>> BODC
>>> 
>>> _  ________________________________ _
>>> This message (and any attachments) is for the recipient only. NERC is
>>> subject to the Freedom of Information Act 2000 and the contents of this
>>> email and any reply you make may be disclosed by NERC unless it is
>>> exempt from release under the Act. Any material supplied to NERC may be
>>> stored in an electronic records management system.
>>> 
>>> 
>>> _______________________________________________
>>> CF-metadata mailing list
>>> CF-metadata at cgd.ucar.edu
>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>>> 
>> _______________________________________________
>> CF-metadata mailing list
>> CF-metadata at cgd.ucar.edu
>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>
>------------------------------------
>John Graybeal
>Senior Data Manager, Metadata and Semantics
>
>T +1 (408) 675-5545
>F +1 (408) 616-1626
>skype: graybealski 
>
>Marinexplore
>920 Stewart Drive
>Sunnyvale, CA
>
>
>
>_______________________________________________
>CF-metadata mailing list
>CF-metadata at cgd.ucar.edu
>http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata

Received on Wed Aug 28 2013 - 12:59:27 BST