11/8/2007HDF and HDF-EOS Workshop XI, Landover, MD1 Software to access HDF5 Datasets via OPeNDAP...

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


MD 2


MD 3

Previous HDF5-Previous HDF5-OPeNDAP SupportOPeNDAP Support

DAP

Prototyped Server No Client

HDF5


MD 4

First Year

DAP

HDF5HDF5 serverClients: Matlab etc.

Proposed work

Current Status


MD 5

DAP

HDF5HDF5 serverClients: Matlab etc.


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


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


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


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!


MD 10In Progress !

Using OPeNDAP Clients to serve HDF5 data

• Matlab Client – in progress• Testing OPeNDAP Clients to read NASA

HDF-EOS5 filesFerretncBrowseIDVODCGrADS


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


MD 12

HDF5 OPeNDAP Website• URL:

http://hdfdap.hdfgroup.uiuc.edu:8080/


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


MD 14

Demo• Ferret• NCBrowser• IDV


MD 15


MD 16

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


MD 17


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.

11/8/2007HDF and HDF-EOS Workshop XI, Landover, MD1 Software to access HDF5 Datasets via OPeNDAP...

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