[netcdfgroup] Announcing netCDF version 4.2.1 release candidate

• To: netcdfgroup@xxxxxxxxxxxxxxxx
• Subject: [netcdfgroup] Announcing netCDF version 4.2.1 release candidate
• From: Russ Rew <russ@xxxxxxxxxxxxxxxx>
• Date: Tue, 19 Jun 2012 12:38:02 -0600

Hi,

The Unidata netCDF group is pleased to announce a release candidate for
version 4.2.1 of the netCDF C libraries, available from either of

  ftp://ftp.unidata.ucar.edu/pub/netcdf/netcdf-4.2.1-rc1.tar.gz
  ftp://ftp.unidata.ucar.edu/pub/netcdf/netcdf-4.2.1-rc1.zip

The release notes are available from

  http://www.unidata.ucar.edu/netcdf/release-notes-4.2.1-rc1.html

This release contains two important new features as well as other
performance enhancements, bug fixes, and documentation improvements.  It
is designed to be compatible with existing netCDF data and software.

The first new feature is portability to Windows platforms, both 32-bit
and 64-bit.  From the same source used for other platforms, you can now
build static or shared libraries (DLL's) for 32- or 64-bit Windows that
include support for DAP remote access, netCDF-3, and netCDF-4/HDF5
compatibility.  The environment for this build is MSYS/MinGW/MinGW64,
and the resulting DLLs may be used with Visual Studio.  We have plans to
continue integrating Windows support for even simpler integration with
Windows Visual Studio builds by using CMake as the build system in a
subsequent release of C-based netCDF.  We will also be including support
for using Fortran with Windows in an upcoming version of the netCDF
Fortran package.

The second new feature is diskless netCDF "files" for all netCDF
formats, implemented with no API changes except an extra mode flag on
file creation or open.  For file creation, diskless operation performs
all operations in memory and then optionally persists the results to a
file on close. For opening an existing disk file, but only for netcdf
classic files, diskless operation caches the file in-memory, performs
all operations on the memory resident version and then writes all
changes back to the original file on close.

For files that will fit in memory, the diskless feature can improve
performance significantly for some kinds of data manipulation, such as

  - converting record variables to use fixed-size dimensions and
    contiguous storage for faster variable-at-a-time access

  - rechunking storage to match common access patterns, for example
    fast time-series access for data organized with time as the slowest
    varying dimension

Please test the release candidate and let us know of problems you find.
This release fixes a number of bugs, described in the release notes.

As a reminder, the C, Fortran, and C++ libraries are no longer bundled
together.  Fortran and C++ releases depend on the netCDF C library, and
may be built after the C library is built and installed.  The latest
Fortran and C++ libraries are compatible with this C library release
candidate, and will benefit from some of its improvements.

--Russ
--Dennis
--Ward