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HDF5 OPeNDAP Project Update and Demo

HDF5 OPeNDAP Project Update and Demo. MuQun Yang and Hyo -Kyung Lee (The HDF Group) James Gallagher ( OPeNDAP , Inc.). OPeNDAP Review . A software framework that allows simple access to remote data Data Access Protocol Client-server model Widely used by Earth Science Community.

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HDF5 OPeNDAP Project Update and Demo

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  1. HDF5 OPeNDAP ProjectUpdate and Demo MuQun Yang and Hyo-Kyung Lee (The HDF Group) James Gallagher (OPeNDAP, Inc.) HDF and HDF-EOS Workshop XII

  2. OPeNDAP Review • A software framework that allows simple access to remote data • Data Access Protocol • Client-server model • Widely used by Earth Science Community HDF and HDF-EOS Workshop XII

  3. OPeNDAP Concept View Data (User) Data (HDF4) Visualization tools (e.g. GrADS) Visualization Tools (gradsdap) Handler (hdf4_handler) Client Library (libnc-dap) Server (apache) DAP Proctocol (Internet) HDF and HDF-EOS Workshop XII

  4. Example Usage HDF4 OPeNDAP Client OPeNDAP HDF4 Server Actual Content of Data Semantic Meaning of Data Syntactic Structure of Data OPeNDAP Visualization Client HDF and HDF-EOS Workshop XII

  5. Why is HDF5-OPeNDAP Project important? • HDF5: NASA EOS / NPOESS • NASA’s MISSION: ACCESS! • Our MISSION: Build a DAP-HDF5 Bridge HDF and HDF-EOS Workshop XII

  6. OPeNDAP HDF5 Server Goal: Access HDF5 data via OPeNDAP • Map HDF5 Datatypesto DAP Datatypes • Plus, some enhancements to allow OPeNDAP Clients to access HDF-EOS5 Files HDF and HDF-EOS Workshop XII

  7. Challenges Mapping HDF5 Datatypes to DAP Datatypes • Compound Datatype • Support for Group • Object/regional References HDF and HDF-EOS Workshop XII

  8. Some OPeNDAP Clients Not all OPeNDAP clients are created equal! • Need special variable names and attributes on dataset. • Need shared geolocation variables outside Grid. HDF and HDF-EOS Workshop XII

  9. Tweaks for OPeNDAP Clients • Two server configuration options • --enable-short-name • --enable-CF HDF and HDF-EOS Workshop XII

  10. HDF EOS5 Not all HDF5 files are created for DAP! • Grid with No Geolocation data • Clients expect Grid with Geolocation data • Some Attributes stored as Extremely Long String(s) (e.g. StructMetada.0) • Clients expect structured attributes HDF and HDF-EOS Workshop XII

  11. Tweaks for HDF-EOS • Two more server configuration options • --enable-eos-grid • --enable-eos-meta HDF and HDF-EOS Workshop XII

  12. Day After Server Tweaks • Finally, Happy Clients! IDL ncBrowse Ferret MATLAB NCL IDV GrADS ODC HDF and HDF-EOS Workshop XII

  13. Goals • 1st: Access HDF5 via OPeNDAP • The OPeNDAP HDF5 handler was released in March, 2008 at OPeNDAP website http://opendap.org/ • 2nd: Construct HDF5 data from OPeNDAP • Bonus: Help clients to better access EOS Swath data HDF and HDF-EOS Workshop XII

  14. HDF5-Friendly OPeNDAP client library HDF and HDF-EOS Workshop XII

  15. Traditional OPeNDAP client library: It’s an attribute that I don’t understand. I’ll ignore it. Example: Groups in HDF5 HDF5-Friendly OPeNDAP client library: I was waiting for this key attribute to re-construct HDF5 HDF and HDF-EOS Workshop XII

  16. Example: Reference in HDF5 • Important for NPOESS • Object / Regional Reference • Map to DAP URL HDF and HDF-EOS Workshop XII

  17. HDF5-Friendly OPeNDAP Client Library • One more reason: Help Clients to view Swath No Latitude and Longitude • Only ODC can display Swath properly. Courtesy of NASA HDF and HDF-EOS Workshop XII

  18. HDF5-Friendly OPeNDAP Client Library NetCDFOPeNDAP Client Library ??? View G/R/Swath View NetCDF NetCDF Group/Ref/Swath View HDF5 HDF5 gradsoc gradsdap OPeNDAP NC Server OPeNDAP HDF5 Server libnc-dap liboc-dap Dap server libdap HDF and HDF-EOS Workshop XII

  19. Summary of Client Library Prototype • Finished coding • Tested with the GrADS visualization client • Documented • Working on a demo DAP to HDF5 tool by using the client library prototype • Will test with NCL if time allows HDF and HDF-EOS Workshop XII

  20. Example: dap2h5 • A test application for the client library • It can construct HDF5 from DAP output ORIGINAL CONSTRUCTED HDF and HDF-EOS Workshop XII

  21. Demo: MLS swath via GrADS • GrADScoupled with our client library • The client library provides grid mapping from swath data • GrADS displays swath through HDF-EOS5 specific client library API calls HDF and HDF-EOS Workshop XII

  22. Caution • Our Client Library is ONLY PROTOTYPE! • It does NOT support all DAP data types • It does NOT support all AURA files • It does NOT support all Visualization clients HDF and HDF-EOS Workshop XII

  23. Summary • HDF5 Access via OPeNDAP • Is Easy • Is used by GES DISC to serve Aura files • HDF5-Friendly OPeNDAP Client Library Prototype • Serves HDF5 better(EOS swath) • Benefits visualization clients HDF and HDF-EOS Workshop XII

  24. Future Work • HDF5 to DAP2 Mapping Document • Release HDF5-friendly OPeNDAP Client Library Prototype • URL: http://hdfgroup.org/projects/opendap HDF and HDF-EOS Workshop XII

  25. Credits Mike Folk (The HDF Group) Robert McGrath (NCSA) Peter Leonard, Daniel Kahn, Marghi Hopkins (ADNET) Christopher Lynnes, James Johnson, Denis Nadeau, Fan Fang (NASA) Jennifer Adams (GrADS) Dave Brown (UCAR) HDF and HDF-EOS Workshop XII

  26. Acknowledgement • This work was supported basing upon the Cooperative Agreement with the National Aeronautics and Space Administration (NASA) under NASA grant NNX06AC83A and NNX06AG75A. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of NASA.  HDF and HDF-EOS Workshop XII

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