-------------------------------------------------------------------------- To subscribe/unsubscribe to the hdfnews mailing list, please send your request to ncsalist@ncsa.uiuc.edu with the appropriate command (e.g. subscribe hdfnews, unsubscribe hdfnews, help) in the *body* of the message. -------------------------------------------------------------------------- Newsletter #23 December 9, 1996 CONTENTS . HDF 4.1 Beta 1 Release A. New Features and Changes B. Platforms Tested C. Known Problems D. Important Fixes . The NCSA Collaborative HDF Viewer . How HDF mixes with Java . New Tools from Users HDF 4.1b1 Release ----------------- HDF 4.1 Beta 1 is now available on the NCSA anonymous ftp server (ftp.ncsa.uiuc.edu) in the directory HDF/HDF_4.1b1/. A. New Features and Changes: o Attributes are now supported in both the vdata and vgroup APIs. In the vdata API, attributes can be attached to either vdata fields or vdatas; in the vgroup API, attributes can be attached to vgroups. This new functionality can be used to attach attributes to vdatas and vgroups created by earlier versions of the HDF library. However, the old versions of the HDF library cannot read the new version vdatas and vgroups. A vdata/vgroup having attributes will become a new version vdata/vgroup. For more information, please refer to the file ../release_notes/vattr.txt, as well as the man pages for the new functions. o Data chunking is now supported in SD scientific data sets. When data chunking is used, an n-dimensional SDS is stored as a series of n-dimensional chunks, improving performance on certain types of partial read operations. New routines for creating and manipulating chunked SD scientific data sets have been provided, and two preexisting SD I/O routines, SDreaddata and SDwritedata, have also been modified to work with chunked SDSs. For more information, please refer to the file ../release_notes/sd_chunk_examples.txt, as well as the man page for sd_chunk. More information will be included in the HDF 4.1 documentation, which will be available with the release of HDF 4.1. o Due to certain limitations in the way compressed SDS datasets are stored, data which has been compressed is not completely writable in ways that uncompressed datasets are. The "rules" for writing to a compressed dataset are as follows: (1) Write an entire dataset that is to be compressed. i.e. build the dataset entirely in memory, then write it out with a single call. (2) Append to a compressed dataset. i.e. write to a compressed dataset that has already been written out by adding to the unlimited dimension for that dataset. (3) For users of HDF 4.1, write to any subset of a compressed dataset that is also chunked. Please refer to the ../release_notes/comp_SDS.txt file for more information. o A new file, ../release_notes/compile.txt, contains instructions on compiling applications on the supported platforms. If you encounter problems with it, please let us know at hdfhelp@ncsa.uiuc.edu. o SGI has changed some compiler default settings in IRIX 6.2. We decided to explicitly define the settings of various ABI related options. For the 64 bit OS ("uname -s" returns IRIX64), HDF uses "-64 -mips4" code. For the traditional 32 bit OS ("uname -s" returns IRIX), HDF uses "-32 -mips2". To use n32 mode on IRIX64, HDF uses "-n32 -mips3" code. Note that in the previous release (4.0r2), HDF used only "-n32". In IRIX 6.1 and before, "-n32" defaulted to "-mips4" code but in IRIX 6.2, it defaults to mips3 or mips4 code. We decided to explicitly set it to "-n32 -mips3". Therefore, applications linking with the HDF library must be compiled with the same explicit ABI options. B. Platforms Tested: HDF 4.1b1 has been tested on the following platforms: DEC Alpha/Digital Unix 3.2 DEC Alpha/OpenVMS AXP v6.2 DEC VAX OpenVMS v6.2 Free BSD 2.2 HP-UX 9.03 IRIX 5.3 IRIX 6.2_64 IRIX 6.2_n32 Linux ELF 1.2.13 (C only) Macintosh PowerPC (C only) (not ready yet) SP2 4.1 Solaris 2.5 SunOS 4.1.3 Windows NT/95 (C only) YMP 9.0.2asC C. Known Problems: o With the SD interface, you are unable to overwrite existing compressed data, that is not stored in "chunked" form. This is due to compression algorithms not being suitable for "local" modifications in a compressed datastream. For more information, please refer to the ../release_notes/comp_SDS.txt file. o With 4.0r1p1, you could type "hdp list -a " to get a list of the file attributes associated with a file. This does not currently work. o There are no plans to add the DF24writeref function to the DF24 interface. This function will be removed from the documentation. o When running "make test" on OpenVMS, Test 3 (float32) of the chunking tests fails, and has therefore been commented out. o When running the tests on Window NT/95, Test 2 (uint16) of the chunking tests fails, and will be commented out. o The ncgen test failed on VAX/OpenVMS. D. Important Fixes: o If you opened a file in Read Only mode with the SD interface (using SDstart), it would create the file if the file did not exist. This no longer occurs. o HDF 4.0r2 did not recognize JPEG images created by HDF 3.3r4. This has been fixed. See the ../release_notes/bug_fixed.txt file for more information on bugs fixed in this release. The NCSA Collaborative HDF Viewer --------------------------------- An alpha demonstration release of the NCSA Collaborative HDF Viewer is now available. The Collaborative HDF Viewer was created by adapting the stand-alone NCSA Java-based HDF Browser to use the NCSA Habanero Collaborative Framework. For information refer to: http://hdf.ncsa.uiuc.edu/hdf/java/chdv/index.html How HDF Mixes With Java ----------------------- In the last few months, the HDF group has been mulling over what to do with Java and HDF. Our investigation has led us to learn more than we really wanted to know about wrapping C libraries with Java and about Java's impoverished data types (compared to C). We still don't have a definite plan, but we do have some notes on what we've learned: http://hdf.ncsa.uiuc.edu/horizon/java-and-hdf.html Many of the comments are relevant to any Java application that wants to wrap existing C libraries, so they may be useful to others. We'd welcome feedback, expressions of interest, and pointers to similar work. New Tools From Users -------------------- Several users have let us know about new tools they have developed that use HDF. For more information on tools that users have developed, please refer to the "What Tools use HDF?" section off of our home page (http://hdf.ncsa.uiuc.edu/tools.html). If you have an application that you would like to add to the list, just let us know at hdfhelp@ncsa.uiuc.edu. HDFLook HDFLook is a friendly Motif HDF viewer, useful for quality control of Scientific Datasets. It allows easy access to physical values and ancillary data, and includes 2-D graphics (radial, histogram). It is currently available for Alpha VMS 3.2, HP-UX 10.1, IRIX 5.3, and AIX. (ftp://loaser.univ-lille1.fr/) WIM Windows Image Manager (WIM) is a general purpose image display and analysis tool for the Microsoft Windows graphical user interface, with special features for analyzing satellite images. (URL: http://spode.ucsd.edu/) HDF Browser Fortner Research has developed the HDF Browser, which is a free utility that lets you open an HDF file, examine its hierarchy and components, and then view and edit its pieces. It runs on Macintosh and Windows NT/95. (URL: http://www.fortner.com/docs/product_hdf_b.html)