Re: Question about CDM

Pauline Mak wrote:
Hi all,

Thanks for the help - through the second validator, I think I've found out what's wrong with the dataset. Some of the axis doesn't have any values under the regular column. I've written a little Java app that goes through a directory and find all nc files and checks that a) it opens up as a GriddedDataset and then 2) the GridCoordSystem from the GriddedDataset isRegularSpatial(). Is this what it means by the WCS standard that it has to be gridded and regularly spaced?

yes. I think WCS 1.1 relaxes the regular spacing need, which will implement later this year (probably).



On 4/21/07, *Ethan Davis* <edavis@xxxxxxxxxxxxxxxx <mailto:edavis@xxxxxxxxxxxxxxxx>> wrote:

    Hi Pauline,

    Another resource for validating datasets against the CDM is available at

    And I believe it is distributed with all TDS installations, so you could
    try it locally at http://yourserver:port/thredds/cdmValidate.html

    Which datasets can be served by the TDS depends on the service over
    which you want to make them available. The HTTP bulk file download
    service (/thredds/fileServer/) can serve any file. The OPeNDAP service
    (/thredds/dodsC/) can serve any dataset that the netCDF-java library
    read (the file types that can be read are listed on the home page, The WCS service
    currently only handles gridded data. The key here is that they have to
    be recognized as gridded datasets by the netCDF-java library. The
    library can recognize gridded data and the coordinates in the data using
    a few different conventions. As Tom and/or Roy mentioned, CF is the
    convention we recommend. The CDM validator above should give you more
    clues on how well you dataset validates.

    Hope that helps.


    Pauline Mak wrote:
     > Hi all,
     > I'm currently setting up a THREDDS server to server our
    datasets.  The
     > setup was fairly easy!  However, I'm running into problems with
     > files which doesn't conform to the "Common Data (Access) Model" - we
     > want to serve all of our data through WCS (which comes for free with
     > THREDDS data server!).  I've searched high and low for documentation
     > on how to 'correct'  incompatible files. but failed to come up with
     > anything.  Am I missing something? Should all NetCDF files "just
     > with the NetCDF-Java 2.2 library?  I'm aware that files should be
     > gridded and regular.  Am I understanding correctly that gridded means
     > the files should have an x and y axis with optional z and t?   Is
     > there a nice method to find out if a file is compatible and if it's
     > not compatible, why it is so?
     > My understanding of NetCDF file is rather shallow... so please bear
     > with me if I'm asking a simple question...
     > Thanks & cheers,
     > -Pauline.
     > --
     > Pauline Mak
     > Software Developer, Insight4
     > Suite 2 / Level 1, 114 Murray St.
     > Hobart, Australia 7000
     > p:  (03) 6234 5203
     > f:  (03) 6234 5603
     > pauline@xxxxxxxxxxxx <mailto:pauline@xxxxxxxxxxxx>
    <mailto:pauline@xxxxxxxxxxxx <mailto:pauline@xxxxxxxxxxxx>>

    Ethan R. Davis                                Telephone: (303) 497-8155
    Software Engineer                             Fax:       (303) 497-8690
UCAR Unidata Program Center E-mail: edavis@xxxxxxxx <mailto:edavis@xxxxxxxx>
    P.O. Box 3000
Boulder, CO 80307-3000

Pauline Mak
Software Developer, Insight4
Suite 2 / Level 1, 114 Murray St.
Hobart, Australia 7000
p:  (03) 6234 5203
f:  (03) 6234 5603
pauline@xxxxxxxxxxxx <mailto:pauline@xxxxxxxxxxxx>

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