using a friendly opendap client library to access hdf5 data muqun yang and hyo-kyung lee (the hdf...
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Using a Friendly OPeNDAP Client Library to Access
HDF5 Data
MuQun Yang and Hyo-Kyung Lee
(The HDF Group)
125th IIPS Conference01/14/2009
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OPeNDAP Review
• A software framework that allows simple access to remote data• Data Access Protocol• Client-server model• Widely used by Earth Science Community
225th IIPS Conference01/14/2009
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Client Library(libnc-dap)
DAP Protocol (via http)
Server(apache)
Handler(hdf4_handler)
Remote Data(HDF4)
View Data (User)
OPeNDAP Concept
325th IIPS Conference01/14/2009
Visualization Tools
(gradsdap)
Typical Remote Access
FTP/HTTP
Visualization tools
(e.g. grads)
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DAP Protocol (via http)
Server(apache)
Remote HDF5View Data (User)
OPeNDAP HDF5 Handler
425th IIPS Conference01/14/2009
HDF5 Handler
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DAP Protocol (via http)
Server(apache)
View Data (User)
OPeNDAP HDF5 Handler with HDF-EOS5
525th IIPS Conference01/14/2009
HDF5 Handler
Remote HDF5
Client Library(libnc-dap)
Visualization tools
(grads)
Remote HDF-EOS5
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HDF5 Handler
DAP Protocol (via http)
Server(apache)
View Data (User)
OPeNDAP HDF5 Handler with HDF-EOS5
625th IIPS Conference01/14/2009
HDF5 Handlerw/ CF options
Remote HDF5
Client Library(libnc-dap)
Visualization tools
(grads)
Remote HDF-EOS5
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Day After Server Tweaks
• Finally, Happy Clients!
725th IIPS Conference01/14/2009
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HDF5-Friendly OPeNDAP Client Library
825th IIPS Conference01/14/2009
DAP Protocol (via http)
Server(apache)
View Data (User)
HDF5 Handler
Client Library(libnc-dap)
Visualization tools
(grads)
Remote HDF5
HDF5 Handlerw/ CF options
HDF5-FriendlyClient Library(liboc-dap)
HDF5 GroupsView Groups???
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Example: Groups in HDF5Traditional 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
925th IIPS Conference01/14/2009
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Example: Reference in HDF5
• Important for NPOESS
• Object / Regional Reference
• Map to DAP URL
1025th IIPS Conference01/14/2009
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• One more reason:
Help Clients to view Swath
Our Client Library(prototype)
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HDF5 Handler
DAP Protocol (via http)
Server(apache)
View Data (User)
Visualizing HDF-EOS5 Grids
1225th IIPS Conference01/14/2009
HDF5 Handlerw/ CF option
Remote HDF5
Client Library(libnc-dap)
Visualization tools
(grads)
Remote HDF-EOS5
Swath
Visualizing HDF-EOS5 Swath Problem
???
HDF5-FriendlyClient Library(liboc-dap)
Visualization Tools
(gradsoc)
View Swath
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Demo: MLS swath via GrADS
01/14/2009 25th IIPS Conference 13
CO at these elevations is a measure of pollution
lower stratosphere
upper stratosphere
Before
After
CO level near Beijing, China before, during and after Olympics
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Summary
• HDF5 Access via OPeNDAP Is easy Is used by NASA GES DISC to serve
Aura files
• HDF5-Friendly OPeNDAP Client Library Is a prototype Serves HDF5 better(EOS swath) Benefits visualization clients
1425th IIPS Conference01/14/2009
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Credits
1525th IIPS Conference01/14/2009
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Acknowledgement
This work was supported basing upon the Cooperative Agreement with the National Aeronautics and Space Administration (NASA) under NASA grant NNX06AC83A, NNX08A077A 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.
1625th IIPS Conference01/14/2009