Prior to this PR, DAP4 always fetched the whole (constrained) dataset
This PR changes the query processing so
1. It reads data on a per-variable request (equivalent to calling nc_get_var()).
2. It tracks a response for every query.
Most of the changes reflect having to do per-variable requests.
In any case, doing all this significantly reduces the amount of data transmitted and hence speeds up DAP4 requests.
## Improvements to S3 Documentation
* Create a new document *quickstart_paths.md* that give a summary of the legal path formats used by netcdf-c. This includes both file paths and URL paths.
* Modify *nczarr.md* to remove most of the S3 related text.
* Move the S3 text from *nczarr.md* to a new document *cloud.md*.
* Add some S3-related text to the *byterange.md* document.
Hopefully, this will make it easier for users to find the information they want.
## Rebuild NCZarr Testing
In order to avoid problems with running make check in parallel, two changes were made:
1. The *nczarr_test* test system was rebuilt. Now, for each test.
any generated files are kept in a test-specific directory, isolated
from all other test executions.
2. Similarly, since the S3 test bucket is shared, any generated S3 objects
are isolated using a test-specific key path.
## Other S3 Related Changes
* Add code to ensure that files created on S3 are reclaimed at end of testing.
* Used the bash "trap" command to ensure S3 cleanup even if the test fails.
* Cleanup the S3 related configure.ac flag set since S3 is used in several places. So now one should use the option *--enable-s3* instead of *--enable-nczarr-s3*, although the latter is still kept as a deprecated alias for the former.
* Get some of the github actions yml to work with S3; required fixing various test scripts adding a secret to access the Unidata S3 bucket.
* Cleanup S3 portion of libnetcdf.settings.in and netcdf_meta.h.in and test_common.in.
* Merge partial S3 support into dhttp.c.
* Create an experimental s3 access library especially for use with Windows. It is enabled by using the options *--enable-s3-internal* (automake) or *-DENABLE_S3_INTERNAL=ON* (CMake). Also add a unit-test for it.
* Move some definitions from ncrc.h to ncs3sdk.h
## Other Changes
* Provide a default implementation of strlcpy and move this and similar defaults into *dmissing.c*.
re: PR https://github.com/Unidata/netcdf-c/pull/2088
re: PR https://github.com/Unidata/netcdf-c/pull/2130
replaces: https://github.com/Unidata/netcdf-c/pull/2140
Changes:
* Add NCZarr-specific quantize functions to the dispatch table.
* Copy (modified) quantize code from libhdf5 to NCZarr
* Add quantize invocation to zvar.c
* Add support for _QuantizeBitgroomNumberOfSignificantDigits
and _QuantizeGranularBitgroomNumberOfSignificantDigits to ncgen.
* Modify nc_test4/tst_quantize.c to allow it to be used both for hdf5
and for nczarr.
* Make dap4 properly handle quantize functions in dispatch table.
* Add quantize attribute support to ncgen.
Other changes:
* Caught and fixed some S3 problems
* Fixed some nczarr fillvalue problems.
* Fixed some nczarr cache problems.
* Cleanup some flaws in libdispatch/dinfermodel.c
* Allow byterange requests to S3 be readable by dinfermodel.c/check_file_type
* Remove the libnczarr ztracedispatch code (big change).
re: https://github.com/Unidata/netcdf-c/issues/2117
re: https://github.com/Unidata/netcdf-c/issues/2119
* Modify libsrc to allow byte-range reading of netcdf-3 files in private S3 buckets; this required using the aws sdk. Also add a test case.
* The aws sdk can sometimes cause problems if the Awd::ShutdownAPI function is not called. So at optional atexit() support to ensure it is called. This is disabled for Windows.
* Add documentation to nczarr.md on how to build and use the aws sdk under windows. Currently it builds, but testing fails.
* Switch testing from stratus to the Unidata bucket on S3.
* Improve support for the s3: url protocol.
* Add a s3 specific utility code file: ds3util.c
* Modify NC_infermodel to attempt to read the magic number of byte-ranged files in S3.
## Misc.
* Move and rename the core S3 SDK wrapper code (libnczarr/zs3sdk.cpp) to libdispatch since it now used in libsrc as well as libnczarr.
* Add calls to nc_finalize in the utilities in case atexit is disabled.
* Add header only json parser to the distribution rather than as a built source.
## S3 Related Fixes
* Add comprehensive support for specifying AWS profiles to provide access credentials.
* Parse the files "~/.aws/config" and "~/.aws/credentials to provide credentials for the HDF5 ROS3 driver and to locate default region.
* Add a function to obtain the currently active S3 credentials. The search rules are defined in docs/nczarr.md.
* Provide documentation for the new features.
* Modify the struct NCauth (in include/ncauth.h) to replace specific S3 credentials with a profile name.
* Add a unit test to test the operation of profile and credentials management.
* Add support for URLS of the form "s3://<bucket>/<key>"; this requires obtaining a default region.
* Allows the specification of profile and/or region in a URL of the form "#mode=nczarr,...&aws.region=...&aws.profile=..."
## Misc. Fixes
* Move the ezxml code to libdispatch so that it can be used both by DAP4 and nczarr.
* Modify nclist to provide a deep clone operation.
* Modify ncuri to provide a deep clone operation.
* Modify the .rc file format to allow the specification of a path to be tested when looking for an entry in the .rc file.
* Ensure that the NC_rcload function is called.
* Modify nchttp to support setting request headers.
The netcdf-c code has to deal with a variety of platforms:
Windows, OSX, Linux, Cygwin, MSYS, etc. These platforms differ
significantly in the kind of file paths that they accept. So in
order to handle this, I have created a set of replacements for
the most common file system operations such as _open_ or _fopen_
or _access_ to manage the file path differences correctly.
A more limited version of this idea was already implemented via
the ncwinpath.h and dwinpath.c code. So this can be viewed as a
replacement for that code. And in path in many cases, the only
change that was required was to replace '#include <ncwinpath.h>'
with '#include <ncpathmgt.h>' and then replace file operation
calls with the NCxxx equivalent from ncpathmgr.h Note that
recently, the ncwinpath.h was renamed ncpathmgmt.h, so this pull
request should not require dealing with winpath.
The heart of the change is include/ncpathmgmt.h, which provides
alternate operations such as NCfopen or NCaccess and which properly
parse and rebuild path arguments to work for the platform on which
the code is executing. This mostly matters for Windows because of the
way that it uses backslash and drive letters, as compared to *nix*.
One important feature is that the user can do string manipulations
on a file path without having to worry too much about the platform
because the path management code will properly handle most mixed cases.
So one can for example concatenate a path suffix that uses forward
slashes to a Windows path and have it work correctly.
The conversion code is in libdispatch/dpathmgr.c, and the
important function there is NCpathcvt which does the proper
conversions to the local path format.
As a rule, most code should just replace their file operations with
the corresponding NCxxx ones defined in include/ncpathmgmt.h. These
NCxxx functions all call NCpathcvt on their path arguments before
executing the actual file operation.
In some rare cases, the client may need to directly use NCpathcvt,
but this should be avoided as much as possible. If there is a need
for supporting a new file operation not already in ncpathmgmt.h, then
use the code in dpathmgr.c as a template. Also please notify Unidata
so we can include it as a formal part or our supported operations.
Also, if you see an operation in the library that is not using the
NCxxx form, then please submit an issue so we can fix it.
Misc. Changes:
* Clean up the utf8 testing code; it is impossible to get some
tests to work under windows using shell scripts; the args do
not pass as utf8 but as some other encoding.
* Added an extra utf8 test case: test_unicode_path.sh
* Add a true test for HDF5 1.10.6 or later because as noted in
PR https://github.com/Unidata/netcdf-c/pull/1794,
HDF5 changed its Windows file path handling.
re: https://github.com/Unidata/netcdf-c/issues/1876
and: https://github.com/Unidata/netcdf-c/pull/1835
and: https://github.com/Unidata/netcdf4-python/issues/1041
The change in PR 1835 was correct with respect to using %20 instead of '+'
for encoding blanks. However, it was a mistake to assume everything was
unencoded and then to do encoding ourselves. The problem is that
different servers do different things, with Columbia being an outlier.
So, I have added a set of client controls that can at least give
the caller some control over this. The caller can append
the following fragment to his URL to control what gets encoded before
sending it to the server. The syntax is as follows:
````
https://<host>/<path>/<query>#encode=path|query|all|none
````
The possible values:
* path -- URL encode (i.e. %xx encode) as needed in the path part of the URL.
* query -- URL encode as needed in the query part of the URL.
* all -- equivalent to ````#encode=path,query````.
* none -- do not url encode any part of the URL sent to the server; not strictly necessary, so mostly for completeness.
Note that if "encode=" is used, then before it is processed, all encoding
is turned of so that ````#encode=path```` will only encode the path
and not the query.
The default is ````#encode=query````, so the path is left untouched,
but the query is always encoded.
Internally, this required changes to pass the encode flags down into
the OC2 library.
Misc. Unrelated Changes:
* Shut up those irritating warning from putget.m4
cloud using a variant of the Zarr protocol and storage
format. This enhancement is generically referred to as "NCZarr".
The data model supported by NCZarr is netcdf-4 minus the user-defined
types and the String type. In this sense it is similar to the CDF-5
data model.
More detailed information about enabling and using NCZarr is
described in the document NUG/nczarr.md and in a
[Unidata Developer's blog entry](https://www.unidata.ucar.edu/blogs/developer/en/entry/overview-of-zarr-support-in).
WARNING: this code has had limited testing, so do use this version
for production work. Also, performance improvements are ongoing.
Note especially the following platform matrix of successful tests:
Platform | Build System | S3 support
------------------------------------
Linux+gcc | Automake | yes
Linux+gcc | CMake | yes
Visual Studio | CMake | no
Additionally, and as a consequence of the addition of NCZarr,
major changes have been made to the Filter API. NOTE: NCZarr
does not yet support filters, but these changes are enablers for
that support in the future. Note that it is possible
(probable?) that there will be some accidental reversions if the
changes here did not correctly mimic the existing filter testing.
In any case, previously filter ids and parameters were of type
unsigned int. In order to support the more general zarr filter
model, this was all converted to char*. The old HDF5-specific,
unsigned int operations are still supported but they are
wrappers around the new, char* based nc_filterx_XXX functions.
This entailed at least the following changes:
1. Added the files libdispatch/dfilterx.c and include/ncfilter.h
2. Some filterx utilities have been moved to libdispatch/daux.c
3. A new entry, "filter_actions" was added to the NCDispatch table
and the version bumped.
4. An overly complex set of structs was created to support funnelling
all of the filterx operations thru a single dispatch
"filter_actions" entry.
5. Move common code to from libhdf5 to libsrc4 so that it is accessible
to nczarr.
Changes directly related to Zarr:
1. Modified CMakeList.txt and configure.ac to support both C and C++
-- this is in support of S3 support via the awd-sdk libraries.
2. Define a size64_t type to support nczarr.
3. More reworking of libdispatch/dinfermodel.c to
support zarr and to regularize the structure of the fragments
section of a URL.
Changes not directly related to Zarr:
1. Make client-side filter registration be conditional, with default off.
2. Hack include/nc4internal.h to make some flags added by Ed be unique:
e.g. NC_CREAT, NC_INDEF, etc.
3. cleanup include/nchttp.h and libdispatch/dhttp.c.
4. Misc. changes to support compiling under Visual Studio including:
* Better testing under windows for dirent.h and opendir and closedir.
5. Misc. changes to the oc2 code to support various libcurl CURLOPT flags
and to centralize error reporting.
6. By default, suppress the vlen tests that have unfixed memory leaks; add option to enable them.
7. Make part of the nc_test/test_byterange.sh test be contingent on remotetest.unidata.ucar.edu being accessible.
Changes Left TO-DO:
1. fix provenance code, it is too HDF5 specific.
* For URL paths, the new approach essentially centralizes all information
in the URL into the "#mode=" fragment key and uses that value
to determine the dispatcher for (most) URLs.
* The new approach has the following steps:
1. canonicalize the path if it is a URL.
2. use the mode= fragment key to determine the dispatcher
3. if dispatcher still not determined, then use the mode flags
argument to nc_open/nc_create to determine the dispatcher.
4. if the path points to something readable, attempt to read the
magic number at the front, and use that to determine the dispatcher.
this case may override all previous cases.
* Misc changes.
1. Update documentation
2. Moved some unit tests from libdispatch to unit_test directory.
3. Fixed use of wrong #ifdef macro in test_filter_reg.c
[I think this may fix an previously reported esupport query].
re: https://github.com/Unidata/netcdf-c/issues/1373 (partial)
* Mark some global constants be const to indicate to make them easier to track.
* Hide direct access to the ncrc_globalstate behind a function call.
* Convert dispatch tables to constants (except the user defined ones)
This has some consequences in terms of function arguments needing to be marked
as const also.
* Remove some no longer needed global fields
* Aggregate all the globals in nclog.c
* Uniformly replace nc_sizevector{0,1} with NC_coord_{zero,one}
* Uniformly replace nc_ptrdffvector1 with NC_stride_one
* Remove some obsolete code
re: issue https://github.com/Unidata/netcdf-c/issues/1251
Assume that you have the URL to a remote dataset
which is a normal netcdf-3 or netcdf-4 file.
This PR allows the netcdf-c to read that dataset's
contents as a netcdf file using HTTP byte ranges
if the remote server supports byte-range access.
Originally, this PR was set up to access Amazon S3 objects,
but it can also access other remote datasets such as those
provided by a Thredds server via the HTTPServer access protocol.
It may also work for other kinds of servers.
Note that this is not intended as a true production
capability because, as is known, this kind of access to
can be quite slow. In addition, the byte-range IO drivers
do not currently do any sort of optimization or caching.
An additional goal here is to gain some experience with
the Amazon S3 REST protocol.
This architecture and its use documented in
the file docs/byterange.dox.
There are currently two test cases:
1. nc_test/tst_s3raw.c - this does a simple open, check format, close cycle
for a remote netcdf-3 file and a remote netcdf-4 file.
2. nc_test/test_s3raw.sh - this uses ncdump to investigate some remote
datasets.
This PR also incorporates significantly changed model inference code
(see the superceded PR https://github.com/Unidata/netcdf-c/pull/1259).
1. It centralizes the code that infers the dispatcher.
2. It adds support for byte-range URLs
Other changes:
1. NC_HDF5_finalize was not being properly called by nc_finalize().
2. Fix minor bug in ncgen3.l
3. fix memory leak in nc4info.c
4. add code to walk the .daprc triples and to replace protocol=
fragment tag with a more general mode= tag.
Final Note:
Th inference code is still way too complicated. We need to move
to the validfile() model used by netcdf Java, where each
dispatcher is asked if it can process the file. This decentralizes
the inference code. This will be done after all the major new
dispatchers (PIO, Zarr, etc) have been implemented.
generates garbage. This in turn interferes with using .netrc
because the garbage user+pwd can will override the
.netrc. Note that this may work ok sometimes
if the garbage happens to start with a nul character.
2. It turns out that the user:pwd combination needs to support
character escaping. One reason is the user may contain an '@' character.
The other is that modern password rules make it not unlikely that
the password will contain characters that interfere with url parsing.
So, the rule I have implemented is that all occurrences of the user:pwd
format must escape any dodgy characters. The escape format is URL escaping
of the form %XX. This applies both to user:pwd
embedded in a URL as well as the use of HTTP.CREDENTIALS.USERPASSWORD
in a .dodsrc/.daprc file. The user and password in .netrc must not
be escaped. This is now documented in docs/auth.md
The fix for #2 actually obviated #1. Now, internally, the user and pwd
are stored separately and not in the user:pwd format. They are combined
(and escaped) only when needed.
Specific changes:
1. Add dap4 code: libdap4 and dap4_test.
Note that until the d4ts server problem is solved, dap4 is turned off.
2. Modify various files to support dap4 flags:
configure.ac, Makefile.am, CMakeLists.txt, etc.
3. Add nc_test/test_common.sh. This centralizes
the handling of the locations of various
things in the build tree: e.g. where is
ncgen.exe located. See nc_test/test_common.sh
for details.
4. Modify .sh files to use test_common.sh
5. Obsolete separate oc2 by moving it to be part of
netcdf-c. This means replacing code with netcdf-c
equivalents.
5. Add --with-testserver to configure.ac to allow
override of the servers to be used for --enable-dap-remote-tests.
6. There were multiple versions of nctypealignment code. Try to
centralize in libdispatch/doffset.c and include/ncoffsets.h
7. Add a unit test for the ncuri code because of its complexity.
8. Move the findserver code out of libdispatch and into
a separate, self contained program in ncdap_test and dap4_test.
9. Move the dispatch header files (nc{3,4}dispatch.h) to
.../include because they are now shared by modules.
10. Revamp the handling of TOPSRCDIR and TOPBUILDDIR for shell scripts.
11. Make use of MREMAP if available
12. Misc. minor changes e.g.
- #include <config.h> -> #include "config.h"
- Add some no-install headers to /include
- extern -> EXTERNL and vice versa as needed
- misc header cleanup
- clean up checking for misc. unix vs microsoft functions
13. Change copyright decls in some files to point to LICENSE file.
14. Add notes to RELEASENOTES.md
