Peter Cao, National Center for Supercomputing Applications

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HDF Web-Browser Plug-in
Peter Cao, National Center for Supercomputing
Applications
This work is supported in part by a Cooperative
Agreement with the National Aeronautics and Space
Agency (NASA) and National Center for
Supercomputing Applications (NCSA)
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Outline

• Plug-in Basics
• Development issues
• An example windows plug-in for IE5

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What Is HDFView

• A browser plug-in is a software program that
  extends the power of Web browser by adding more
  features and supporting more types of content
  than what the standard browser provides
• An HDF browser Plug-in is a windowed Plug-in that
  is launched from Web browser to display HDF4 and
  HDF5 files

Web Browser
New Datatype
Plug-ins
New Feature
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Reasons for a HDF Plug-in

• Click-and-view by clicking on or drag-drop a HDF
  file, the browser will recognize and display the
  file (much like the acrobat reader plug-in for
  pdf files)
• Easy install and update downloading and
  installing the plug-in is just a simple click. No
  uninstall and reinstall is necessary for new
  release. Users will be asked for automatic update
  when a new version is released
• Browse remote files with predefined the MIME
  type, the plug-in will take the advantage of the
  web browser to browse HDF files over the internet

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How Plug-ins Works

• A standard set of plug-in APIs are defined for
  communication between applications and the
  browser
• Netscape Plug-in APIs
• Microsoft ActiveX controls

Plug-in Java C C
Web Browser Internet Explorer Netscape
Mozilla
HDF Library
Browser Side Plug-in API
Plug-in Side Plug-in API
HDF File
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Implementation Challenge

• Plug-ins are platform and browser dependent
• Platforms
• Windows
• Mac
• Linux
• Solaris
• Browsers
• Internet Explorer
• Netscape or Mozilla

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Implementation Challenge continue
Since Microsoft has removed support for Netscape
plug-ins from IE 5.5 SP 2 and beyond, plug-ins
developed in Netscape Plug-in APIs will not work
on IE. Netscape/Mozilla does not support ActiveX
controls
NS Plug-in APIs
Microsoft ActiveX
IE 5.5 SP 2
Netscape/Mozilla
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Choice Microsoft ActiveX

• Pros
• Better performance (speed and memory)
• Easy installation (one piece software)
• Works best for IE, which has 80 of the users
• Cons
• Works only on IE and Windows.
• Maintenance and support

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Choice Java Pluglet API
A Pluglet is a Plug-in that is written in Java
and a close 11 implementation of the C
Plug-in API in Mozilla
Pluglet
Pluglet Engine (Java)
JVM
Pluglet Engine (C)
Plug-in API (NS API)
ActiveX
IE
Mozilla
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Choice Java Pluglet API continue

• Pros
• Support all major platforms
• Easy maintenance (reuse HDFView code)
• Cons
• Lower performance (Java ? C)
• Requires Java Runtime Environment
• Installation (classpath, JNI path, security)

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Short Demo Plug-in For IE
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Questions