Hello Steve,
Responses interleaved.
Best,
cz
Le 18/09/2013 09:32, Steve Hankin a ?crit :
>
>
> On 9/18/2013 7:56 AM, Roy Mendelssohn - NOAA Federal wrote:
>> Hi All:
>>
>> NASA has used hierarchies for years, and appears committed to them. So, either it is done in an ad hoc way, or through a standard. That doesn't mean CF is the place for the standard, just that it would be nice to have one.
>
> Roy,
>
> Lets explore the avenue you have opened here: "/that doesn't mean CF is
> the place for the standard/". The need for hierarchies as tools for
> programming is indisputable. But will hierarchical groups advance the
> interoperability objectives of CF? At the start of this discussion I
> had assumed that there would be compelling examples that supported the
> introduction of hierarchies to CF. Thus far all that have been put on
> display seem to be counter-examples(*):
>
> * For CMIP5 any given hierarchy is an arbitrary, brittle
> representation. The CMIP5 collection is better modeled by facets
> (metadata tags) than by hierarchies.
This is a bold assertion. Different ways of "modeling" multi-model
ensembles are in different contexts. It is true that CMIP5 is currently
served/represented as a collection of flat granules.
> * The suitcase analogy serves best to illustrate the _problems_ that
> hierarchies can bring -- to locate the black socks in a suitcase
> usually involves rummaging the entire suitcase.
> o ==> Which speaks to Rich's valid concern that the
> data-discovery-to-data-access transition may be very negatively
> impacted if hierarchies are not used carefully.
> * NASA hierarchies that are 10 levels deep strike me as by definition
> an "insider" view of a data collection. These hierarchies may add
> clarity for the specific satellite program communicating with its
> designated science groups, but they are likely a barrier to an
> outsider wanting to utilize the data.
We do not endorse NASA's current use of hierarchical data as "best
practices" :) Yes, those datasets I mentioned do exist. The
show that important numbers/volumes of hierarchical datasets are
"in the wild". Until/unless better conventions are created/adopted,
it will remain a fragmented wilderness.
>
> To proceed forward we need to see some compelling use cases that will
> help us to understand the costs and benefits?
I agree that one or more consensus use-cases which
are appropriate for CF are indispensable.
Please comment on new thread
Are ensembles a compelling use case for "group-aware" metadata?
>
> - Steve
>
> (*) with the exception of Feature Collections types already contained in CF
>
--
Charlie Zender, Earth System Sci. & Computer Sci.
University of California, Irvine 949-891-2429 )'(
Received on Thu Sep 19 2013 - 14:14:00 BST
