Thanks John, though I'm now a bit confused I think.. ;-(
True:
nj22 implements the CDM data access layer
the CDM data access layer is the same as the NetCDF-4 data model
Not true (yet):
nj22 implements NetCDF-4
Details:
When the NetCDF-4 file format is finalized (waiting on HDF5-1.8), then
nj22 will be able to read NetCDF-4. It will not immediately be able to
write, and depending on how complicated things are (HDF5 is pretty
complicated, esp compared to netcdf-3), it may end up only only writing
a subset of netcdf-4. I would guess eventually it will write the whole
thing, but that will depend on funding. There has never been an
independent library that writes (or reads) HDF5, so we are wary of
promising what hasnt been done before. We have prototyped HDF5 reading
enough to know we can do that.
Hang-on, I thought that the HDF5 stuff was required to implement the new
features in the netCDF-4 data model? Certainly that is how I understand
things to be in the netCDF-4.0-alpha libraries -- to use 'netCDF-4
format' requires HDF5-1.8 (or 1.7.52), though of course things may be
different in the nj22 world. What storage model does nj22 use to
implement the CDM data access layer if not HDF5? Does nj22 extend the
netCDF-3 file format to support eg multiple unlimited dimensions etc? or
does it not support all of the netCDF-4 data model? (is the CDM data
access layer a subset of the netCDF-4 data model?)
What am I missing?
thanks
Simon Wood
--
Simon Wood Meteorology & Remote Sensing
Scientific Programmer NIWA
simon.wood@xxxxxxxxxx http://www.niwa.co.nz
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