Re: 950623: DDI and NetCDF

>Keywords: 199506231604.AA06535

Hi Michael,

>       Hello.  I am a research assistant at Albany's Atmospheric Sciences
> Research Center (ASRC) for Dr. Wei-Chyung Wang.  Our climate modeling division
> has obtained a copy of DDI ( Data and Dimensions Interface ) from 
> Lawrence Livermore National Laboratory.  However, in order for DDI
> to accept our data files, they must be in DRS, HDF, or NetCDF format.
> I ftp'ed a copy of NetCDF over to ASRC with the intentions
> of converting our files to NetCDF format and thus making them
> DDI compatibile.  Am I going about this in the right way and exactly how
> can I put our files in NetCDF format?  All our data files are direct access
> gridded data using regularly spaced grids ( R15 and T31 ), with a format
> based on the format used in NCAR data files.  

I think your approach sounds fine.  You will have to write a program to do
the conversion, since I am not aware of any programs that handle this
conversion automatically.  The program should read data in the format in
which it currently exists and write it out in netCDF form, using the
interfaces provided by the netCDF library.  Alternatively if there is a
great deal of data and you will only be looking at a small subset of it with
DDI but you cannot anticipate in advance which data will be of interest, you
might attempt to write an program that would convert data "on-the-fly", when
it is accessed.  This is a more ambitious undertaking that might require
writing a server for the data and client code that provides the netCDF
interface to DDI but actually uses remote procedure calls to the server to
get the data.  A project that is implementing something similar is the DODS
project, a description of which may be found at 

    http://dcz.gso.uri.edu/

>       Could you also tell me what the file libsrc/test_cdf.sav is, since
> this file is the only one that DDI seems to accept so far?

It's just a small test file used in testing whether the library was built OK
when you build and install the library according to the instructions in the
netCDF/INSTALL document.  It gets used as part of the series of tests that 
"make test" invokes.  Other netCDF test files are created during these
tests, but none are particularly useful for other purposes.

______________________________________________________________________________

Russ Rew                                           UCAR Unidata Program
address@hidden                              http://www.unidata.ucar.edu