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

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we just use "application/x-netcdf" in the TDS, following the "keep it simple" principle. im not sure if encoding the convention in the mime type is all that helpful (?)

On 10/12/2011 7:38 AM, Lorenzo Bigagli wrote:
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:

 1. CF extension to the netCDF core standard (Stefano Nativi)
 2. CF-netCDF extension to the WCS core standard (Stefano Nativi)
 3. Enhanced Data Model extension to the netCDF core standard
    (Ben Domenico)
 4. Uncertainty model for netCDF-CF (Lorenzo Bigagli and Stefano Nativi)
 5. 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 <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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