1. HDF5 OPeNDAP Project Update and Demo MuQun Yang and Hyo-Kyung Lee (The HDF Group) James Gallagher (OPeNDAP, Inc.)

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

3. Example Usage OPeNDAP Client OPeNDAP HDF4 Server HDF4 Syntactic Structure of Data Semantic Meaning of Data Actual Content of Data OPeNDAP Visualization Client

4. Why Important? HDF5: NASA EOS / NPOESS ACCESS! NASA’s MISSION : ACCESS! Our MISSION: Build a DAP-HDF5 Bridge

5. OPeNDAP HDF5 Server 1.Map HDF5 Datatypes into DAP Datatypes 2.Plus, tweaks for OPeNDAP Clients 3.Plus, tweaks for HDF-EOS Files Goal: Access HDF5 data via OPeNDAP

6. Mapping HDF5 Datatypes Prototype server in 2001 NASA Grant from Nov. 2006 Support for Compound Datatype Support for Group Support for References / Links First Product Release in Mar. 2008

7. OPeNDAP HDF5 Server 1.Map HDF5 Datatypes in DAP Datatypes 2.Plus, tweaks for OPeNDAP Clients 3.Plus, tweaks for HDF-EOS Files Goal: Access HDF5 data via OPeNDAP

8. OPeNDAP Clients I hate long variable names. I need special attributes on dataset. I care only Grid datatypes. I care only well-formed attributes. Not all OPeNDAP clients are created equal!

9. Tweaks for OPeNDAP Clients Two configuration options --enable-short-name --enable-CF

10. OPeNDAP HDF5 Server 1.Map HDF5 Datatypes in DAP-way 2.Plus, tweaks for OPeNDAP Clients 3.Plus, tweaks for HDF-EOS5 Files Goal: Transform HDF5 access in DAP-way

11. HDF EOS Grid with No Dimension data  Clients expect Grid with Dimension data Some Attributes stored in Extremely Long String(s) (e.g. StructMetada.0)  Clients expect well-structured attributes Not all HDF5 files are created for DAP!

12. Tweaks for HDF-EOS Two more configuration options --enable-eos-grid --enable-eos-meta

13. Day After Server Tweaks Finally, Happy Clients!

14. Goals 1st : Access HDF5 via OPeNDAP 2nd: Construct HDF5 data from OPeNDAP Bonus: Help clients to better access EOS Swath data

15. Some Things Hard: Opaque, Bitmap, Enum, Variable Length types Illegal: Reserved characters in DAP are used in Dataset/Group name in HDF5 (that OPeNDAP HDF5 server can’t serve)

16. For Everything Else Let there be HDF5-Friendly OPeNDAP client library! Package and Deliver in DAP first. Then, let the client library handle it.

17. Example: Group in HDF5 Traditional OPeNDAP client library: It’s an attribute that I don’t understand. I’ll ignore it. HDF5-Friendly OPeNDAP client library: I was waiting for this key attribute to re-construct HDF5

18. Example: Reference in HDF5 Object / Regional Reference Map to DAP URL Important for NPOESS

19. One more reason: Help Clients to view Swath Only ODC can display Swath properly. HDF5-Friendly OPeNDAP Client Library Easy but Rigid OPeNDAP NC Client Library!  easy: same as netCDF C interface  rigid: follows netCDF model Our client library must be Easy but Flexible No Latitude and Longitude Courtesy of NASA

20. libnc-dap ??? liboc-dap NC-Friendly OPeNDAP Client Library libdap dapserver OPeNDAP NC Server GrADS NetCDFView NetCDF HDF5 Group/Ref/Swath OPeNDAP HDF5 Server View HDF5 GrADS View G/R/Swath HDF5-Friendly OPeNDAP Client Library

21. Example: dap2h5 A test application for the client library It can construct HDF5 from DAP output

22. Demo: GrADS GrADS is modified to use our library The client library provides grid mapping from swath data GrADS displays swath through HDF-EOS5 specific client library API calls

23. 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

24. Summary HDF5 Access via OPeNDAP Is Easy / Efficient / Cool Loses some things Requires HDF5-friendly OPeNDAP Client Library HDF5-Friendly OPeNDAP Client Library Prototype Serves HDF5 better(EOS swath) Benefits visualization clients

25. Future Work HDF5 to DAP2 Mapping Document Release HDF5-friendly OPeNDAP Client Library Prototype URL: h ttp://hdfgroup.org/projects/opendap/index.html

26. Credits Mike Folk (THG) 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)

27. 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.