Transitions from HDF4 to HDF5: Issues
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Transitions from HDF4 to HDF5: Issues
- 1. Transition from HDF4 to HDF5: Issues Robert E. McGrath NCSA University of Illinois at Urbana-Champaign University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 1 HDF
- 2. Overall Goal A discussion of compatibility, conversion, and interoperability issues for HDF4 and HDF5, and HDFEOS. For more details see the white paper at: http://hdf.ncsa.uiuc.edu/HDF5/doc/TechNotes/TransitionIssues.pdf University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 2 HDF
- 3. Conclusions (Preview) Transition from HDF4 to HDF5 is not necessarily transparent or effortless. University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 3 HDF
- 4. Conclusions: HDF • Transition from HDF4 to HDF5 is not transparent: in most cases source code will have to be written or rewritten. • Many tools will support both HDF4 and HDF5. • Default translation from HDF4 to HDF5 will be supported as a utility and library. University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 4 HDF
- 5. Conclusions: HDF-EOS • Transition from HDFEOS2 to HDFEOS3 is not transparent: in most cases source code will have to be written or rewritten • Translation of ‘pure’ HDF-EOS will be supported • Translation of ‘hybrid’ HDF-EOS files is very difficult. • Not possible to support V.2 and V.3 in a single program University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 5 HDF
- 6. What Does Compatibility Mean? University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 6 HDF
- 7. What does “compatibility” mean? • Ability to “do the same things” with new software – I.e., “compatibility” is relative to some purpose – Many dimensions and shades of compatibility – No golden solution sufficient for every use • Assume HDF4 users want to continue doing what they are already doing, but move to HDF5 University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 7 HDF
- 8. Some Types of Compatibility Compatibility Issue Conceptual Description Format Software Programming model Features Interfaces The overall conceptual approach: the formal and informal models. Storage layout and other format details. Compatibility of the software The assumptions and approach to programming. The set of features supported. The programming interfaces. University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 8 HDF
- 9. Compatibility of HDF and HDF-EOS Compatibility Issue HDF4/HDF5 HDFEOS2/HDFEOS3 Conceptual Yes, H5 is a Yes superset Format No No Software Programming model No? Yes Features Some Yes, V3 is a superset Interfaces No No University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 9 HDF
- 10. Interoperation • My definition of “interoperation”: one program or tool may use HDF4 or HDF5 or both University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 10 HDF
- 11. NCSA HDF4 and HDF5 University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 11 HDF
- 12. Interoperability: Any program may use either HDF4 or 5 or both: Not Supported dataset1 dataset2 image1 image2 Single Combined HDF Library HDF 4 Library HDF 5 Library Stored as HDF4 Objects Stored as HDF5 Objects HDF4 file HDF5 file University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 12 HDF
- 13. Interoperability: Specific Application or tool may use either HDF4 or 5 or both: Up to Application and Tool Developers dataset1 dataset2 image1 image2 Application Specific Library specific HDF 4 Library HDF 5 Library Stored as HDF4 Objects Stored as HDF5 Objects HDF4 file HDF5 file University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 13 HDF
- 14. HDF-EOS Version 2 and Version 3 University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 14 HDF
- 15. Interoperability: Any program may using HDF-EOS Objects with either HDF4 or HDF5 or both: Not supported HDFEOS Library Grid1 Grid2 HDF 4 Library Grid3 Grid4 HDF 5 Library Stored as HDF4 Objects Stored as HDF5 Objects HDF4 file HDF5 file University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 15 HDF
- 16. Interoperability: One application may use HDF-EOS Objects with either HDF4 or HDF5 or both: Not supported Grid1 Grid2 HDFEOS V2 Library HDF 4 Library Grid3 Grid4 HDFEOS V3 Library HDF 5 Library Stored as HDF4 Objects Stored as HDF5 Objects HDF4 file HDF5 file University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 16 HDF
- 17. Translation • Convert HDF4 objects (file) to HDF5 objects (file) University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 17 HDF
- 18. Translation of HDF4 to HDF5 Supported: NCSA mapping and h4toh5 tool and library HDF4 Library HDF5 Library / Stored as HDF4 Objects Stored as Analogous HDF5 Objects HDF5 File HDF4 File University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 18 HDF
- 19. Translation of HDF-EOS V2 to V3 Supported HDF EOS V. 2.x Library Grid1 Grid2 HDF EOS V. 3 Library Grid2 Grid1 SAME HDFEOS Objects HDFEOS Objects HDF4 Library HDF5 Library Stored as HDF4 Objects Stored as HDF5 Objects / HDF5 file HDF4 file University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 19 HDF
- 20. “Hybrid” HDF-EOS files • HDF-EOS files may contain native HDF objects (images, arrays, etc.) as well as HDF-EOS objects (Grid, etc.) • Almost all HDF-EOS files are ‘hybrids’. • Very difficult to automatically translate hybrid files. University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 20 HDF
- 21. “Hybrid” HDF-EOS File Science Application Code HDFEOS Other NCSA HDF Components of HDFEOS Objects stored in HDF Objects Other HDF Objects Stored Directly Through HDF One HDF file, objects mixed together. Very difficult to tell which objects are part of HDF-EOS University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 21 HDF
- 22. Conclusions Transition from HDF4 to HDF5 is not necessarily transparent or effortless. University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 22 HDF
- 23. Conclusions: HDF • Transition from HDF4 to HDF5 is not transparent: in most cases source code will have to be rewritten. • Many tools will support both HDF4 and HDF5. • Default translation from HDF4 to HDF5 will be supported as a utility and library. University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 23 HDF
- 24. Conclusions: HDF-EOS • Transition from HDFEOS2 to HDFEOS3 is not transparent: in most cases source code will have to be rewritten • Translation of ‘pure’ HDF-EOS will be supported • Translation of ‘hybrid’ HDF-EOS files is very difficult. • Not possible to support V.2 and V.3 in a single program University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 24 HDF
- 25. For More Information • NCSA White paper: “Transition From HDF4 to HDF5”: http://hdf.ncsa.uiuc.edu/HDF5/doc/TechNotes/TransitionIssues.pdf • “Guidelines for Mapping HDF4 to HDF5 Objects”, http://hdf.ncsa.uiuc.edu/HDF5/papers/H4-to-H5MappingGuidelines.pdf • h4toh5 tool: Soon University of Illinois at Urbana-Champaign 9/19/2000 McGrath 9/19/2000 25 HDF