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Chapter 1: Introduction

1.1 Overview
1.2 JHV Features
1.3 Limitations
1.4 System Requirements
1.5 Installing and Running JHV


1.1 Overview

The Java™ HDF Viewer (JHV) is a Java-based visualization tool for browsing NCSA Hierarchical Data Format (HDF) files. JHV allows users to browse through any HDF file; starting with a view of all top-level objects in an HDF file's hierarchy, JHV allows a user to descend through the hierarchy and navigate among the file's data objects. The content of a data object is loaded only when the object is selected, providing interactive and efficient access to HDF files.

The JHV user interface is designed to be easy to use and intuitive. JHV was implemented by using Java that is designed to be machine-independent. The interface and features are the same for all platforms. The structure of the HDF file is displayed in a tree with data groups and data objects represented as conventional folders and icons. You can easily expand or collapse folders to navigate the hierarchical structure of an HDF file.

1.2 JHV Features

JHV version 2.2 has the following features. Limitations on these features are listed in the next section.

1.3 Limitations

The current implementation of JHV has the following limitations. Many of these limitations are scheduled for resolution in the next JHV release, currently targeted for October 1998.

1.4 System Requirements

To run JHV, a Java 1.1.x Virtual Machine, such as JDK-1.1.6, is required and 24MB RAM is recommended. JHV version 2.2 has been built and is available on the following platforms:

1.5 Installing and Running JHV

JHV is distributed from the
NCSA Java-based Products page at http://hdf.ncsa.uiuc.edu/java-hdf-html/.

The JHV distribution is available in two forms:

  1. A self-contained package, complete with the Java Runtime Environment (JRE). This package can be installed and run with no other software. (About 18 MB)
  2. A ready-to-run Java application, which can run on any system which has Java installed. (About 3 MB)
In both cases, this step will install a JHV directory structure on your system. The README file in the top level of that structure contains the following instrctions for running JHV.

For the self-contained package, this is all than is needed. For the ready-to-run package, the Java environment needs to be set up:

UNIX environment
To run JHV on a UNIX system, first set the following environment variables:
  1. CLASSPATH -- add the path to the NCSA JHI/JHV classes,
    e.g. setenv CLASSPATH /usr/local/jhv/lib/classes.zip:$CLASSPATH
  2. LD_LIBRARY_PATH -- add the path to the NCSA JHI/JHV libraries,
    e.g. setenv LD_LIBRARY_PATH /usr/local/jhv/lib:$LD_LIBRARY_PATH
  3. PATH -- add the path to the NCSA JHI/JHV binaries,
    e.g. setenv PATH /usr/local/jhv/bin:$PATH
Then start JHV by typing jhv at a command line prompt.

Windows 95/NT environment
The following steps are required to run JHV on a Windows 95/NT system:
  1. Set the variable JHVHOME in the JHV batch file jhv.bat (in your_jhv_home\bin).
  2. If needed, set the variable JAVAHOME.
  3. Create a shortcut to the JHV executable, if desired.
  4. Start JHV by double-clicking on the executable icon or on the shortcut, or by typing jhv at the DOS command prompt.
If you get the error message "Out of environment space" when running jhv.bat under Windows 95, you need to set the Initial Environment memory allocated to the command line to 4096 bytes as follows:
  1. Open the Windows Explorer.
  2. Open the JHV home directory.
  3. Open the bin directory.
  4. Right click on the jhv.bat icon.
  5. Select Properties from the menu.
  6. Click the Memory tab.
  7. Find Initial Environment.
  8. Click the arrow next to the field.
  9. Scroll to and select 4096.
  10. Click OK .
For more information, see the instructions at the NCSA Java-based Products page at http://hdf.ncsa.uiuc.edu/java-hdf-html/.


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NCSA
The National Center for Supercomputing Applications

University of Illinois at Urbana-Champaign

hdfhelp@ncsa.uiuc.edu