Hi Sean:
Ive already made a fix in the 4.4.0 branch to preserve the global
attribute Conventions=CF.1-x if that exists in the source file. Easy to
do and its the right thing.
More difficult is to guarentee that all CF semantics get preserved in
the translation. The subsetting process has to change the coordinate
system, but we try to pass everything else through. Let us know any
issues and we will try to fix. We are looking at the ones that Seth has
reported.
The problem is that the damn software has to be told exactly what to do!
"Read the CF Conventions document", I said. Sheesh.
John
On 8/30/2013 1:59 AM, Gaffney, Sean P. wrote:
> Hi John and all,
>
> My initial reaction was the same as Seth's in that I felt
> uncomfortable that any aspect of the metadata was being altered.
> However, if it can be confirmed that only change occurring will be
> the alteration of the Conventions attribute back to 1.0, that is
> something we can handle with a declaration to the user.
>
> As it stands, I've inspected the variables and attributes for the
> model data we've got at present once they've been run through THREDDS
> and so far, there are no actual changes apart from the convention
> being altered from 1.4 on the data we received, back to 1.0 in the
> output. My concern is whether this situation could be guaranteed into
> the future, as we at BODC receive more complex oceanographic model
> data in CF 1.6.
>
> Cheers
>
> Sean
>
> -----Original Message----- From: CF-metadata
> [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of John Caron
> Sent: 29 August 2013 00:19 Cc: cf-metadata at cgd.ucar.edu Subject: Re:
> [CF-metadata] thredds changing CF conventions version
>
> Hi John and all:
>
> For sure its a good idea to preserve the CF Conventions attribute if
> it exists. I will add that to our issue tracker.
>
> Remember that THREDDS is a general purpose subsetter, not specific
> to CF. So we deal with lots of source datasets (eg GRIB) that arent
> CF. The point is that we convert whatever we have to CF.
>
> Up to this point, as CF versions have evolved, there hasnt been any
> difference in the way that we write out these files. So im interested
> if Ive missed something and there is some actual change in the file
> structure that we should be tracking from Sean's POV. Other than the
> actual version number.
>
> John
>
>
> On 8/28/2013 11:11 AM, John Graybeal 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
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>>>>
>>>>
>>>> _______________________________________________ CF-metadata
>>>> mailing list CF-metadata at cgd.ucar.edu
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>>>>
>>> _______________________________________________ CF-metadata
>>> mailing list CF-metadata at cgd.ucar.edu
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>>
>> ------------------------------------ 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
>>
>>
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Received on Fri Aug 30 2013 - 11:33:08 BST
