Hello John,
> As I understand it, your starting concern is to be able to put
> things into folder-equivalents, pure and simple.
Our original post describes my goals. Groups are a logical place to
start because they must exist for inheritance to be meaningful.
I am for having 1. groups as containers, 2. metadata inheritance, and,
eventually, 3. metadata (like "ensemble") that exploits specified
relationships among groups. It sounds like you are for the latter two,
too.
> I wonder if trying to satisfy both needs with one modification will
> produce the cleanest outcome?
I am for _starting_ (not staying) simple.
I explained that the simplest conceivable step toward our goals
is recognizing groups as legitimate containers. Then I constructed a
"straw-man" of how this would be rather silly unless metadata
inheritance were also recognized. Lacking that, each group would need
its own copy of all the file-level metadata like "history" and
"Conventions". Silly, methinks.
The straw-man of groups as containers is only a starting point.
Alone it would not satisfy me, you, or many others.
Perhaps treatments of groups and metadata scope should join the
convention simultaneously, otherwise, as you say, not much point.
I hope the group-as-container-only strawman illustrates one end of the
spectrum of complexity for what could become a longish standard that
should perhaps begin with a few small steps.
cz
Le 17/09/2013 17:08, John Graybeal a ?crit :
>> The simplest support imaginable is that groups should be completely self-contained without attribute inheritance. This would go in the right direction,
>
> My value proposition is rather the opposite. In preparing well-documented netCDF files, I need some kind of inherited attributes, because that is the only explicit way for the data model within the file to reflect the data model within the real world. (And it's the only explicit way for the UI to present to a user that real-world model.)
>
> Using containers to group together a bunch of files is a fine concept, but I feel no need to manipulate standards of an individual file type to let me mimic that -- I can just put together a bunch of files in a directory. (Done!) I'm even less likely to put all these things together into a group, and then say "but the characteristics defined for the group don't apply to the things in it." That makes for an extremely low-cohesion group, and usually a lot of redundant (therefore difficult to manage and process) metadata.
>
> The discussion of flat vs hierarchical advantages in this context is thus lost on me (and I have tons of directories AND smart folders AND use spotlight constantly, and deal with XML and relational DBs all the time).
>
> I want proper, unambiguous modeling of the data relationships using CF. As I understand it, your starting concern is to be able to put things into folder-equivalents, pure and simple.
>
> I wonder if trying to satisfy both needs with one modification will produce the cleanest outcome?
>
> John
>
> On Sep 17, 2013, at 13:51, Charlie Zender <zender at uci.edu> wrote:
>
>> Hi Stephen,
>>
>> I also advocate keeping support for groups simple.
>> The simplest support imaginable is that groups should be completely
>> self-contained without attribute inheritance. This would go in the
>> right direction, yet I think attribute inheritance, at least of global
>> metadata, ought to be strongly considered. Otherwise useful attributes
>> like "history" and "Convention" have to be stored in each group....
>>
>> cz
>>
>>
>> Le 17/09/2013 04:56, stephen.pascoe at stfc.ac.uk a ?crit :
>>> Bryan has beaten me to the points I would have made. I think hierarchies are over rated at the interface level. Examples abound of where they have been abandoned: hierarchal vs relational DBs, XML databases and tools (save us from xquery for Netcdf!).
>>>
>>> Under the hood hierarchies are often necessary for scalability and we all use them as a crutch when no better tools exist.
>>>
>>> I would advocate keeping support for groups very simple. CF could treat any netcdf file containing groups as if it was a directory of netcdf files with attached metadata. IMO complex rules about inter-group relationships should be avoided. I guess attribute inheritance must be an exception here but I would urge caution. One of the CF data model tickets has got a detailed debate on interpretation of the current standard regarding variable attributes overriding global attributes. Lessons from that should be learned.
>>>
>>> Stephen.
>>>
>>> --
>>> Stephen Pascoe from iPhone
>>>
>>
>>
>> --
>> Charlie Zender, Earth System Sci. & Computer Sci.
>> University of California, Irvine 949-891-2429 )'(
>> _______________________________________________
>> 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
>
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>
>
>
>
--
Charlie Zender, Earth System Sci. & Computer Sci.
University of California, Irvine 949-891-2429 )'(
Received on Tue Sep 17 2013 - 20:08:24 BST
