11/8/2007 HDF and HDF-EOS Workshop XI, Landover, MD 1 Software to access HDF5 Datasets via OPeNDAP MuQun Yang, Hyo-Kyung Lee The HDF Group
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 1
Software to access HDF5 Datasets via OPeNDAP
MuQun Yang, Hyo-Kyung LeeThe HDF Group
Previous work review
HDF5-OPeNDAP server:• Incomplete mapping from HDF5 to
OPeNDAP• No comprehensive test suite• Only tested a few examples on two
platforms• Incomplete documentationHDF5-OPeNDAP client:• No client at all
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 2
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 3
Previous HDF5-Previous HDF5-OPeNDAP SupportOPeNDAP Support
DAP
Prototyped Server No Client
HDF5
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 4
First Year
DAP
HDF5HDF5 serverClients: Matlab etc.
Proposed work
Current Status
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 5
DAP
HDF5HDF5 serverClients: Matlab etc.
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 6
HDF5 Server Status – New Features
• Mapping Compound datatype to DAP Structure
• *Mapping EOS Grid to DAP Grid• *Mapping HDF5 group to DAP • *Mapping HDF5 object and
regional references to DAP
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 7
• Code Cleanup – updating to the latest version of HDF5
• Comprehensive testsuite – DejaGNU• Internal Aura EOS file testsuite • Inside OPeNDAP’s nightly build system
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 8
DONE
HDF5 Server Status - Test
HDF5 Server Status – Special Support
• Partial Support of CF conventions• Relative Object Path Support• Configuration Options• HDF5-OPeNDAP handler Website
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 9
DONE
HDF5 Server Status - Documentation
• Mapping HDF5 group to DAP -- Done!• Limitations of HDF5-OPeNDAP handler – In
progress!• Mapping Object reference to DAP – In
Progress!• Experiments with OPeNDAP clients – In
Progress!
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 10In Progress !
Using OPeNDAP Clients to serve HDF5 data
• Matlab Client – in progress• Testing OPeNDAP Clients to read NASA
HDF-EOS5 filesFerretncBrowseIDVODCGrADS
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 11
Several Highlights• HDF5-OPeNDAP Handler Website• Limitations of the current handler• Demo: Visualizing HDF-EOS5 Aura data
with existing OPeNDAP clients• Limitations of the existing clients
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 12
HDF5 OPeNDAP Website• URL:
http://hdfdap.hdfgroup.uiuc.edu:8080/
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 13
Limitations of the handler• No support for HDF5 files that have a '.'
inside a group/dataset name• No support for any variable length types
except for 1 dimensional variable-length string array
• No support for ENUM,BITFIELD,OPAQUE types
• 64 bit integer (array) is not supported• Both signed and unsigned char map to Byte
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 14
Demo• Ferret• NCBrowser• IDV
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MD 15
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Summary of accessing Aura L3G Data via OPeNDAP clients
Client Problem Solution Notes
ncBrowse N/A N/A
2D display only. No way to latitude and longitude information.
Ferret
Geolocation fields should fit into longitude(-180~180) and latitude (-90~90) range
map geolocation value to longitude and latitude
Attributes with units should be provided for correct display.
IDV Strictly Follows CF convention.
Need Short names(<15 characters for variables) and need units for attributes.
Beautiful user interface.
GrADSStrictly Follows CF convention. Maybe 3-D(x,y,time) Grids only?
Renaming grid map data variables?
It entirely depends on libdap-nc client library.
ODC N/A N/AIt can't display data. Data retrieval is OK.
Second year Plan• High-level HDF5 client• Working with GrADS team• We really would like to hear feedbacks
from UsersPlease send emails to
[email protected]@hdfgroup.org
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 17
11/8/2007HDF and HDF-EOS Workshop XI, Landover,
MD 1818
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.