Filter support has three goals:
1. Use the existing HDF5 filter implementations,
2. Allow filter metadata to be stored in the NumCodecs metadata format used by Zarr,
3. Allow filters to be used even when HDF5 is disabled
Detailed usage directions are define in docs/filters.md.
For now, the existing filter API is left in place. So filters
are defined using ''nc_def_var_filter'' using the HDF5 style
where the id and parameters are unsigned integers.
This is a big change since filters affect many parts of the code.
In the following, the terms "compressor" and "filter" and "codec" are generally
used synonomously.
### Filter-Related Changes:
* In order to support dynamic loading of shared filter libraries, a new library was added in the libncpoco directory; it helps to isolate dynamic loading across multiple platforms.
* Provide a json parsing library for use by plugins; this is created by merging libdispatch/ncjson.c with include/ncjson.h.
* Add a new _Codecs attribute to allow clients to see what codecs are being used; let ncdump -s print it out.
* Provide special headers to help support compilation of HDF5 filters when HDF5 is not enabled: netcdf_filter_hdf5_build.h and netcdf_filter_build.h.
* Add a number of new test to test the new nczarr filters.
* Let ncgen parse _Codecs attribute, although it is ignored.
### Plugin directory changes:
* Add support for the Blosc compressor; this is essential because it is the most common compressor used in Zarr datasets. This also necessitated adding a CMake FindBlosc.cmake file
* Add NCZarr support for the big-four filters provided by HDF5: shuffle, fletcher32, deflate (zlib), and szip
* Add a Codec defaulter (see docs/filters.md) for the big four filters.
* Make plugins work with windows by properly adding __declspec declaration.
### Misc. Non-Filter Changes
* Replace most uses of USE_NETCDF4 (deprecated) with USE_HDF5.
* Improve support for caching
* More fixes for path conversion code
* Fix misc. memory leaks
* Add new utility -- ncdump/ncpathcvt -- that does more or less the same thing as cygpath.
* Add a number of new test to test the non-filter fixes.
* Update the parsers
* Convert most instances of '#ifdef _MSC_VER' to '#ifdef _WIN32'
The problem was that for opendap, it is possible to use keywords
as identifiers
when there is no ambiguity. However, the DAP2
parser lost the case of the identifier used the lower case version.
Fix is to use the actual text of the symbol when it is used as an identifier.
Also added a test case for this (kwcase.*).
Additionally cleaned up some misc. dap2 testing problems.
1. ncdap_test/tst_ncdap3.sh was using an empty test set.
restored the testing of datasets.
2. as a consequence of #1, some tests needed to be updated with minor
tweeks.
3. fix dapmerge to handle multiple DODS_EXTRAS attributes.
4. modify buildattribute to suppress nul characters and terminate
the name at the first nul.
5. clean up various test scripts to remove residual, unused
references to obsolete netcdf-4 translation.
6. export e.g. NCDUMP from test_common.in so that non-top-level
shell scripts can access it.
Problem was in oc2/dap.y.
In definition of errormsg:, change WORD_WORD to WORD_STRING
since the msg field of an opendap error response is a quoted
string.
Also took the opportunity to modify ncgen to
transfer the logging level (-L flag) into the c-code
generated using -lc.
User request to have all orphaned DAP2 attributes kept as netcdf
global attributes. This is primarily a change in the oc code
nplus testcase dataset changes.
Result may be inconsistent with netcdf-Java output.
