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A new version of HDF-EOS5, called HDF-EOS V5.1, is now available. This version of HDF-EOS 5 is based on HDF5-1.4.1, and supercedes HDF-EOS V5.0, which was released in March 2001.
This version of HDF-EOS V5.1 is delivered for use in EOS Science Computing Facilities. It has not been tested in the ECS itself; that is, it has not yet been certified that HDF5-based files will operable in ECS subsystems. This testing is planned for ECS release 6.AP, later in 2001.
This version contains several enhancements to the prior version (see Section G, Notes, item 5). The HDF-EOS team heartily thanks Cheryl Craig of the HIRDLS team for testing the software and for finding discrepancies.
We anticipate that ECS will internally support both HDF4 and HDF5-based files by Fall 2001. HDF4 and the currently-released versions of HDF-EOS, which are based on HDF4 (currently V4.1r3), will be supported by ECS at least until 10/2002, the end of the ECS contract.
The ESDIS Project will continue to support HDF4 within EOSDIS for as long as required.
EOS Terra, EOS Aqua and Landsat 7 instruments currently produce HDF4-based data. Currently, EOS-AURA teams and the GLAS instrument team plan to produce HDF5-based data products.
The following is excerpted from the Users Guide for this software library and provides some background on the migration to HDF5 from HDF4. The document is titled, "HDF-EOS Interface Based on HDF5, Volume 1: Overview and Examples", and can be found on http://edhs1.gsfc.nasa.gov
HDF5 is a nearly complete rewrite of HDF4 and contains a different user API and underlying data model. An HDF-EOS library written in conjunction with HDF5 and which uses HDF5 functionality, will necessarily be a rewrite of the HDF4-based version.
The new HDF5-based library will support the same Grid/Point/Swath functionality and to the extent possible it will be built with the same calling sequences as the original library. We will refer to the newer library as HDF-EOS 5.1. The former library is currently designated HDF-EOS 2.7-based. (see The HDF-EOS Library Users Guide for the ECS Project, Volume 1 and Volume 2)
The following future uses for HDF-EOS are anticipated:
HDF-EOS 5.1 support for HDF5 has the same function calls as the current HDF-EOS 2.7-based library, based on HDF4. The main difference is that the functions are prefixed with "HE5_". There are a few additions to the library to account for new HDF5 functionality, such as calls to account for HDF5 implementation of Variable-Length and Compound data types. The parameters in the V5.1 function calls are the same, with a few exceptions.
This implementation entails the fewest possible modifications with respect to retrofitting code, i.e. removing HDF4 file access in favor of HDF5 file access. Users retrofitting old code should anticipate changing variable datatypes to accommodate new HDF5 variable datatypes. The API will make the underlying HDF5 data model transparent otherwise.