HDFView and HDF Java Products
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October 15-17, 2008 HDF and HDF-EOS Workshop XII 1 HDF-Java Products Peter Cao The HDF Group HDF and HDF-EOS Workshop XII October 15, 2008
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This tutorial will introduce the three levels of the HDF-Java products: the HDF-Java wrapper (or Java Native Interfaces to the standard HDF libraries), the HDF-Java object package, and the HDFView. The Java wrapper provides standard Java APIs that allow applications to call the C HDF libraries from Java. The HDF-Java object package implements HDF data objects, e.g. Groups and Datasets, in an object-oriented form and makes it easy for applications to use the libraries. The HDFView is a visual tool for browsing and editing HDF4 and HDF5 files.
Transcript of HDFView and HDF Java Products
October 15-17, 2008 HDF and HDF-EOS Workshop XII 1
HDF-Java Products
Peter Cao
The HDF Group
HDF and HDF-EOS Workshop XII
October 15, 2008
October 15-17, 2008 HDF and HDF-EOS Workshop XII 2
What are the HDF-Java products?
HDF-Java
HDF
JavaWrapper
ObjectPackage
Viewer Editor
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Java Wrapper
HDF
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Java Wrapper
HDF
Pure JavaLibrary
HDF
Java Native Interface
a programming framework that allows Java code to call and be called by applications and libraries written in other languages
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Pure Java Library
• Pros: True platform independence Direct access to file (no data
conversion between C and Java)
HDF
Pure JavaLibrary
• Cons: Substantial amount of work to
implement Hard to maintain (new features or
format changes)
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HDF JNI
• Pros: Easy to implement Easy to maintain
HDF
HDF
Java Native Interface
• Cons: Requires data conversion between C
and Java HDF JNI is platform dependent
Java Wrapper
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HDF Java Native Interface
HDFLibrary.javaH5.java
libjhdf.so (or dll)
libjhdf5.so (or dll)
HDF4 library
HDF5 library
Java Wrapper: C versus Java
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hid_t H5Fcreate (const char *name, unsigned flags, hid_t create_id, hid_t access_id );
hid_t H5Fopen (const char *name, unsigned flags, hid_t access_id );
herr_t H5Fclose (hid_t file_id );
public static native int H5Fcreate (String name,
int flags,int create_id,int access_id);
public static native int H5Fopen (String name,int flags,int access_id);
public static native int H5Fclose (int file_id);
C Java
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Object Package
HDF-Java
HDF
JavaWrapper
ObjectPackage
Viewer Editor
Java Wrapper: simple dataset read
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int fid, did, sid, tid, rank; long dims[], maxDims[]; Object theData;
fid = H5.H5Fopen( fname, HDF5Constants.H5F_ACC_RDWR, HDF5Constants.H5P_DEFAULT); did = H5.H5Dopen(fid, dname); sid = H5.H5Dget_space(did); tid = H5.H5Dget_type(did); rank = H5.H5Sget_simple_extent_ndims(sid); dims = new long[rank]; maxDims = new long[rank]; H5.H5Sget_simple_extent_dims(sid, dims, maxDims); theData = allocateArray(tid, dims); H5.H5Dread( did, tid, HDF5Constants.H5S_ALL, HDF5Constants.H5S_ALL, HDF5Constants.H5P_DEFAULT, theData); H5.H5Sclose(sid); H5.H5Tclose(tid); H5.H5Dclose(did); H5.H5Fclose(fid);
Object Package: the easy way
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theData = Dataset.read();
Object Package: main purposes
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• Simplifies access to HDF files• Separates applications from libraries
Modular design Client server model
• Makes testing and maintenance easy
Object Package: levels of objects
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Common Objectsncsa.hdf.object
jhdfobj.jar
HDF4ncsa.hdf.object.h4
jhdf4obj.jar
HDF5ncsa.hdf.object.h5
jhdf5obj.jar
Abstract classesAbstract classes
ImplementationImplementation
Object Package: abstract classes
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HObjectHObject
CompoundDSCompoundDSScalarDSScalarDS
DatasetDatasetGroupGroup
FileFormatFileFormat
Object Package: HDF4 implementation
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H4GroupH4Group H4GRImageH4GRImageH4SDSH4SDS H4VdataH4Vdata
GroupGroup ScalarDSScalarDS CompounDSCompounDS
FileFormatFileFormat
H4FileH4File
Object Package: HDF5 implementation
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H5GroupH5Group H5ScalarDSH5ScalarDS H5CompoundDSH5CompoundDS
GroupGroup ScalarDSScalarDS CompounDSCompounDS
FileFormatFileFormat
H5FileH5File
Object Package: file create
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import ncsa.hdf.object.*;
public class H5FileCreate{ private static String fname = "H5FileCreate.h5";
public static void main( String args[] ) throws Exception { FileFormat fileFormat = FileFormat.getFileFormat(FileFormat.FILE_TYPE_HDF5);
fileFormat.createFile(fname, FileFormat.FILE_CREATE);
}}
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HDFView
HDF-Java
HDF
JavaWrapper
ObjectPackage
Viewer Editor
HDFView: basic components
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HDFView: GUI components
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HDFView(GUI)TreeView MetaDataView
TableView ImageView TextView
UserImp
UserImpUserImpUserImp
UserImp
HDFView: all together
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What are the HDF-Java products?
HDF-Java
HDF
JavaWrapper
ObjectPackage
Viewer Editor
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This report is based upon work supported in part by a Cooperative Agreement with the National Aeronautics and Space Administration (NASA) under NASA Awards NNX06AC83A and NNX08AO77A. 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 the National Aeronautics and Space Administration.
Thank You!
Questions/comments?
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