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Re: Use of netCDF under Windows

> Organization: Varian Chromatography Systems
> Keywords: 199502102151.AA24288

Hi,

> Over the last few years I have participated in the AIA's effort to develop a 
> chromatography data interchange standard based on netCDF. Most 
> chromatography data systems these days operate under Microsoft Windows, and 
> most participants in the group found that the netCDF code was not easily 
> ported to Windows. I have 2 questions in this regard:
> 
> 
> 1) A very user-friendly approach to create a netCDF-based end-user toolkit 
> for Windows is to create a Dynamic Link Library exporting all netCDF 
> functions. Users can then link to the DLL from a variety of languages 
> including Visual basic. Another advantage of a dynamic link is that in many 
> cases, you can switch to an updated DLL without having to recompile the 
> programs using it. We (at Varian, not the AIA) have created such a DLL and 
> would like to distribute this toolikt to our users. At the last AIA meeting 
> on 2/2/95 we had a conference call with somebody at Unidata (but I don't 
> think it was you) and I asked what legal requirements had to be met in order 
>  to distribute such a toolkit as part of our software. From what I 
> understood, we must include a copyright statement referring to Unidata in 
> the software and the documentation, but we could copyright our version of 
> the software, and sell it, license it out or give it away. We would not pay 
> royalties to Unidata, and we would not be obligated to distribute any part 
> of it freely.
> 
> Is this correct?

It was me at the Unidata side of the conference call.

I've appended a copy of the file named COPYRIGHT in our current software
distribution.  I believe your understanding is correct, but you might want
to have your legal department look at our copyright statement to be sure.
There are already several commercial visualization products that incorporate
netCDF software under these conditions.

> To be specific, one of the DLLs in this toolkit corresponds exactly to the 
> netCDF interface, with code modifications to support operation as a Windows 
> DLL (re-entrancy, etc...). Other libraries contain functions specific to our 
> software.
> 
> 
> 2) In the process of adapting the code to MS-Windows, we have diverged from 
> the original multi-platform code. In the long term, this may lead to major 
> problems, and I think it would be a good idea to merge back. I don't have a 
> good feel for how difficult this would be. Do you have an interest in 
> supporting MS-Windows? It was suggested at the meeting that we might want to 
> wait for Windows '95.

There has been some interest from the netCDF user community (which is larger
than the Unidata community) in a Windows DLL version of the netCDF library.

I also think it would be a good idea to merge the changes required for a DLL
version of netCDF back into our sources, if this is practical.  That way
future versions of the library would continue to work for Windows.

Would it be possible for us to get a copy of the sources for your Windows
DLL version of the netCDF library, to estimate how practical it would be to
merge the two versions?  Alternatively, were you planning to upgrade to our
netCDF 2.3 version and create a DLL version of that?  In either case, we
would be interested in finding out what is necessary to adapt the library to
the Windows environment.  We don't currently have a Windows platform here to
use for testing, but we may have one soon.

______________________________________________________________________________

Russ Rew                                                UCAR Unidata Program
address@hidden                                          P.O. Box 3000
http://www.unidata.ucar.edu/                          Boulder, CO 80307-3000
______________________________________________________________________________


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