A rampaging mob finally convinces me to spend some quality time with DLL development...

Windows DLL versions of the netCDF C library have usually come last in our list of supported platforms. This is not only because it was uncommon among science users, but also because we mostly don't develop in windows, and it's significantly different.

As a result we released DLLs for windows for almost all our versions, but this system broke down after the 4.0 release. Since then, we have not done a windows DLL release, and that is too long.

To try and bring windows into the mainstream of netCDF testing and development, we are now using Cygwin, with mingw32 libraries, to build netCDF DLLs.  This is something I just got working last week. The results can be seen on the daily snapshot page (you must be logged into the Unidata website to view this page):

https://www.unidata.ucar.edu/software/netcdf/builds/snapshot/

The builds on Carson are on a Cygwin machine, and the ones with description field "no OPeNDAP DLL build on Cygwin" are the DLL building tests. (The other tests on Carson are just straight Unix builds on Cygwin.)

The current results show that this is working for the non-netCDF-4 version of the DLL. But what do I mean by "working?" All tests pass, and I am left with a DLL, so that's good. But the DLL is not the whole story, Microsoft developers also need a .lib file, which describes the DLL. There is a way to produce this with my daily build too, and I have to get it working.

There is also the problem that the DLL is named cygnetcdf.dll, and it should be named netcdf.dll. A simple rename, but I have to look into why the tools put the "cyg" there in the first place, to see if it is important.

But, though much work remains to be done, I am happy to be producing a netCDF DLL as part of my daily snapshot. All this is much easier than it used to be, due to steady improvement in Cygwin and mingw32. To build this DLL, the configure must be run with options --enable-dll and --target=mingw32.

The next step is to get an automated binary release of the DLL, so that I can easily get it out to the users. In the meantime, if anyone would like to give it a try, email me and I will send it. This is the C API only, without netCDF-4 or OPeNDAP.

The end goal is to produce netCDF-4 and OPeNDAP capable DLLs, as part of the normal build process, and with the same autoconf/automake tool set we use for all other platforms.