Hello Steve, Responses interleaved.
Best, cz Le 18/09/2013 09:32, Steve Hankin a écrit : > > > 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 )'( _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
