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Re: [galeon] CF-netCDF SWG Session Summary: Sept 2011 TC Meeting

Dear colleagues,

At the last OGC TC Meeting in Boulder, we discussed the issue of registering a 
MIME type for netCDF.
As I remember, someone (at Unidata?) may be drafting a proposal, possibly 
following what's in use for xml.

I've given this an extra thought, while working on UncertWeb and the 
Uncertainty Conventions, that I'm sharing here.

First, as a temporary solution, we are using the "application/x-netcdf" MIME 
subtype.
The biggest issue is with netCDF conventions, since a single netCDF file may 
comply with multiple conventions.
This gets in the way with a possible hierarchical structure of MIME sub-typing, 
like e.g.:
                x-netcdf-<convention1>-<convention2>...

We may take the xml approach of a "+netcdf" suffix, but this wouldn't 
solve/address the problem.
So I would suggest an optional "conventions" parameters with the same syntax 
and semantics as the global "Conventions" attribute in netCDF.
The content-type of a netCDF-U dataset may look like:
        application/x-netcdf; conventions="UW-1.0 CF-1.5"

We may take the same approach with the version, although I'd probably go for an 
"application/x-netcdf-4" subtype, in that case.
I would be interested in comments on this, also to align with what is being 
drafted. 

Best regards,
  Lorenzo


Il giorno 30/set/2011, alle ore 23:18, Ben Domenico ha scritto:

> Hi all,
> 
> The CF-netCDF SWG session was held Thursday morning September 22, 2011 at 
> UCAR in Boulder.  A summary is given below.  If anyone who attended the SWG 
> has additions or corrections, please let us know.
> 
> -- Ben
> 
> ==========================================
> 
> CF-netCDF SWG Session at the September 2011 OGC TC Meetings in Boulder
> 
> Agenda
> 
> The agenda consisted of: 
> CF extension to the netCDF core standard (Stefano Nativi)
> CF-netCDF extension to the WCS core standard (Stefano Nativi)
> Enhanced Data Model extension to the netCDF core standard (Ben Domenico)
> Uncertainty model for netCDF-CF (Lorenzo Bigagli and Stefano Nativi)
> Determine how to deal with errors in existing netCDF binary standard noted by 
> Simon Cox (see next slide)
> Item 5 was taken care of in brief discussions with Carl Reed and Simon Cox 
> outside the SWG session.   They both agree that the changes are not 
> substantive, so the typos can be corrected in the existing spec and a phrase 
> can be inserted clarifying that Requirement 1 is a special type of 
> requirement, namely, a dependency.
> 
> The presentations and draft documents are available at:
> 
> https://portal.opengeospatial.org/index.php?m=projects&a=view&project_id=82&tab=2&artifact_id=45016
> 
> Issues
> 
> A couple additional issues came up during the discussion
> There is a need to register a mime type for netCDF with IANA.  The question 
> is whether to try to come up with all the modifiers (e.g. netCDF-3, netCDF-4, 
> netCDF-CF,…) before submitting request.   The sense of the group is that a 
> base mime type necdf should be registered with modifiers for netCDF-, 
> netCDF-4, CF-netCDF, etc.  
> With the new modular approach to specifications, OGC is creating a bit of a 
> Humpty Dumpty Problem of having too many modules in specs, too many 
> conformance classes within modules, etc.  As a consequence, potential new 
> users can be overwhelmed.  It isn't always clear how to assemble fragments 
> into a coherent, working whole.   Primers with an overall overview are a help 
> by not a solution.  One new possibility is to emphasize the need for overview 
> information in Profile specs where the application to a particular community 
> is documented.
> Action Items (all internal to the SWG)
> Make non-substantive edits to existing netCDF binary encoding spec.  See note 
> in Agenda above.  (Ben Domenico)
> In the CF Extension to netCDF core, some items that are optional for CF are 
> mandatory in the proposed OGC specification.  A list of these items will be 
> circulated with the call for comments. (Stefano Nativi)
> The CF-netCDF overview and planning documents should indicate that 
> XML-encoding is addressed in CF-netCDF extension to WCS. (Ben Domenico)
> Discussion paper for netCDF uncertainty conventions will be captured in a 
> discussion paper for next TC.  Will include netCDF3 and netCDF4 options and 
> will pursue with CF conventions community in parallel (Lorenzo Bigagli)
> Motions
> 
> There were no motions at this SWG
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