Access HDF5 Datasets via OPeNDAP’s Data Access Protocol (DAP) I will introduce a new joint project between the HDF Group and OPeNDAP. The goal of this project is to provide a server and utility so that people can have access to HDF5 Datasets via OPeNDAP. MuQun Yang The HDF Group 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

HDF and HDF-EOS Workshop X, Landover, MD OPeNDAP A software framework that allows simple access to remote data Client-server model Servers make the local data accessible remotely Clients make applications easily access to remote served data Widely used by Earth Science Community URL: http://www.opendap.org/ First a brief introductions of OPeNDAP. 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

HDF and HDF-EOS Workshop X, Landover, MD The Data Request Data are requested with a URL. http://www.cdc.noaa.gov/cgi-bin/nph-nc/datasets/Reynolds_sst Protocol Machine name OPeNDAP server Directory File name ?sst[10:10][0:90][0:180] Constraint The user can impose a constraint on the data that s/he would like to acquire from a data set by appending a constraint expression to the end of the URL. 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

HDF and HDF-EOS Workshop X, Landover, MD OPeNDAP Data Types OPeNDAP provides three basic data objects: data descriptor structure (.dds) - syntactic metadata - rigid data attribute structure (.das) - semantic metadata - flexible data (.dods) - the actual data in a binary structure 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

HDF and HDF-EOS Workshop X, Landover, MD OPeNDAP Servers Data Matlab HDF4 JDBC FreeFrom FITS CDF CEDAR netCDF DSP JGOFS Tables SQL Flat Binary CODAR ESML General No fully-supported HDF5 server 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

HDF and HDF-EOS Workshop X, Landover, MD OPeNDAP Clients netCDF C netCDF Java IDV Ferret GrADS VisAD ncBrowse Matlab Excel IDL Access Client No HDF5 client 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

Why HDF5-OPeNDAP server and client? Users! Users!! Users!!! 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

HDF and HDF-EOS Workshop X, Landover, MD A User Case Task: 10 elements of 17 MB HDF5 data 200 elements of 10 MB NetCDF data 150 elements of 5 MB HDF4 data 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

HDF and HDF-EOS Workshop X, Landover, MD General approach HDF5 data FTP HDF4 data FTP NetCDF data FTP 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

HDF and HDF-EOS Workshop X, Landover, MD Approach with OPeNDAP HDF5 data FTP HDF4 data server DAP client NetCDF data DAP server 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

HDF and HDF-EOS Workshop X, Landover, MD Conclusion HDF5-DAP server is required HDF5-DAP client is strongly recommended 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

Previous work - A Prototype of DAP2-HDF5 server Incomplete mapping from HDF5 to OPeNDAP No comprehensive test suite Only tested a few examples on two platforms Incomplete documentation 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

HDF and HDF-EOS Workshop X, Landover, MD An example from SSMI From HDF4 server at JPL From HDF5 server at NCSA 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

Current HDF5-OPeNDAP Support No Client Prototyped Server 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

HDF and HDF-EOS Workshop X, Landover, MD HDF5-OPeNDAP Project Two-year project awarded by NASA ROSES NRA Funding much less than expected Original proposed work kept with significant contributions from ESDIS Starting date: Nov. 15th, 2006 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

Proposed Work – software development Implementation HDF5-DAP2 server HDF5-DAP4 server Deployment Release servers to OPeNDAP community 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

HDF and HDF-EOS Workshop X, Landover, MD HDF5-DAP2 server Update and complete the prototype, including make files, instructions, documentation, etc Add a few selected features to handle NASA Aura data and NPOESS data Map HDF5 group to DAP(?) Map Object/regional reference to DAP(?) Implement a comprehensive test suite Test on platforms supported by OPeNDAP Demonstrate with sample NASA data 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

Fully-Supported HDF5 Server DAP HDF5 server HDF5 Matlab/Ferret Client DAP 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

Proposed Work – software development Implementation DAP4 to HDF5 conversion utility Deployment Release utility to OPeNDAP community Design study Feasibility of DAP-aware HDF5 library 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

Proposed Work - DAP to HDF5 utility A command line tool that converts DAP to HDF5 file individual DAP variable subsetting Conversion tool HDF5 HDF5 server DAP 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

Proposed work - documentations DAP4 specification HDF5-DAP4 mapping document DAP4 to HDF5 specification RFC for DAP-aware HDF5 library Submit specifications to ESDSWG 11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD

HDF and HDF-EOS Workshop X, Landover, MD Acknowledgement This work was supported basing upon the Cooperative Agreement with the National Aeronautics and Space Administration (NASA) under NASA grant NNG05GC60A.  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.  11/24/2018 HDF and HDF-EOS Workshop X, Landover, MD