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[netCDF #NCE-670062]: How to produce NcML from a netCDF-4 file

Looking at the ncdump.c code, it appears that if the file is of
netcdf-4 format, then ncdump should fail with this message:
"NcML output (-x) currently only permitted for netCDF classic model"
It also appears that if the file is netcdf-4 classic format, then it should
work ok.
 

> 
> As far as I understand, even if a netcdf-4 file is made to look like
> classic (either by adding the _nc3_strict attribute via HDF5 API or running
> nccopy), ncdump -x is not guaranteed to work correctly.
> 
> Is my understanding right?
> 
> In our case ncdump -x appears to work correctly, but this is probably
> because the files we receive from the GOES-R system don't use much of the
> enhanced model.  Does this make sense?
> 
> Just trying to make sure I understand.
> 
> Thank you,
> 
> Anatoli
> 
> address@hidden> wrote:
> 
> > Good Morning Dennis,
> >
> > Thank you for your prompt response.
> >
> > We do not produce the files, we just archive and disseminate them to
> > users.  Some users want NcML representation of the metadata in the files
> > instead of getting the actual files.  My guess would be that they look
> > through small NcML files to decide which ones to order at a later time.
> > Running ncdump -x from netCDF 4.1.1 (old version we are moving away from)
> > produces the same output as running ncdump -x from a more recent version
> > (4.3.3) on a file produced from the original by running nccopy -k "netCDF4
> > classic model" on it.   Unfortunately, ncdump v. 4.3.3 does not support the
> > -x option on these files.
> >
> > Attached is a small GOES-R file of the kind we work with.
> >
> > Thank you,
> >
> > Anatoli
> >
> > address@hidden> wrote:
> >
> >> There is currently no way to do this for netcdf-4 files.
> >> It is doable but would take some time.
> >> Your comment about faking classic makes me think that you
> >> are not using a lot of  the netcdf-4 data model.
> >> Can you describe which netcdf-4 features you are using?
> >>
> >> > Hardware:
> >> > Description of problem: I work on a NOAA project, CLASS, and our
> >> software depends on being able to run ncdump -x to obtain NcML metadata
> >> representation for a GOES-R file, which is reported as netCDF-4 by ncdump
> >> -k.
> >> >
> >> > We are upgrading to a more recent version of netCDF and have found that
> >> the -x option is only supported for the classic model.  I understand we
> >> might be able to circumvent the problem by changing an attribute in the
> >> file to make it appear classic, but we would like to avoid manipulating or
> >> copying files.
> >> >
> >> > Is there a command line utility or an API call that would allow us to
> >> generate NcML from a netCDF-4 file?
> >> >
> >> > Thank you,
> >> >
> >> > Anatoli
> >> >
> >> >
> >>
> >> =Dennis Heimbigner
> >>   Unidata
> >>
> >>
> >> Ticket Details
> >> ===================
> >> Ticket ID: NCE-670062
> >> Department: Support netCDF
> >> Priority: Normal
> >> Status: Open
> >> ===================
> >> NOTE: All email exchanges with Unidata User Support are recorded in the
> >> Unidata inquiry tracking system and then made publicly available through
> >> the web.  If you do not want to have your interactions made available in
> >> this way, you must let us know in each email you send to us.
> >>
> >>
> >>
> >
> 
> 

=Dennis Heimbigner
  Unidata


Ticket Details
===================
Ticket ID: NCE-670062
Department: Support netCDF
Priority: Normal
Status: Open
===================
NOTE: All email exchanges with Unidata User Support are recorded in the Unidata 
inquiry tracking system and then made publicly available through the web.  If 
you do not want to have your interactions made available in this way, you must 
let us know in each email you send to us.