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Basic foilset Overview of TANGO Base Technology

Given by Marek Podgorny at Rome Lab Quarterly Review for CIV on October 1 96. Foils prepared 22 February 97
Outside Index Summary of Material

Summary of Client-based WWW technologies
Inter-technology communication Java/JavaScript/LiveConnect
Role of JavaScript in LiveConnect
Java - native language communication
Java - plug-ins communication
Java - JavaScript communication
Applet - plug-in communication

Table of Contents for full HTML of Overview of TANGO Base Technology

 Denote Foils where Image Critical
Denote Foils where HTML is sufficient
1 Client-based WWW technologies
2 Inter-technology communication
3 PP Presentation
4 Java - native language communication
5 Java - plug-ins communication
6 Java - JavaScript communication
7 Applet - plug-in communication

Outside Index Summary of Material

HTML version of Basic Foils prepared 22 February 97

Foil 1 Client-based WWW technologies

From Overview of TANGO Base Technology Rome Lab Quarterly Review for CIV -- October 1 96. *
Full HTML Index
Java
  • Java is an architecture-neutral programming language, not necessarily bound with WWW.
  • Applets are programs written in Java that are embedded in Web pages (subject to security constraints).
  • JavaScript is a cross-platform scripting language to be embedded directly in HTML page and interpreted by Web browsers.
  • Plug-ins are software modules that are seamlessly integrated into Navigator, appearing as supplemental capabilities of the browser.
  • LiveConnect technology encompasses plug-ins as well as facilities for integrating plug-ins with Java and JavaScript.
HTML version of Basic Foils prepared 22 February 97

Foil 2 Inter-technology communication

From Overview of TANGO Base Technology Rome Lab Quarterly Review for CIV -- October 1 96. *
Full HTML Index
native code - any language linkable with C
Java allows you to:
  • 1. call native methods from Java,2. call Java methods from native code.This does not work (for security reasons) with applets.
  • LiveConnect allows you to:
    • 3. call Java methods from plug-ins,4. call native methods implemented in plug-ins from Java,5. call Java methods from JavaScript,6. call JavaScript from Java methods.
    • We found the way to:
      • 7. call native methods from applets,8. call applet methods from native code.
HTML version of Basic Foils prepared 22 February 97

Foil 3 PP Presentation

From Overview of TANGO Base Technology Rome Lab Quarterly Review for CIV -- October 1 96. *
Full HTML Index
Applet and plug-in learn about each other via JavaScript
Inter-language capabilities
Browser entities communication capabilities
Browser entities cross-awareness
HTML version of Basic Foils prepared 22 February 97

Foil 4 Java - native language communication

From Overview of TANGO Base Technology Rome Lab Quarterly Review for CIV -- October 1 96. *
Full HTML Index
The Java language uses native method modifier to declare a method implemented in another language.The native signature of the method as well as wrapper functions are machine generated using program javah.The class using native method needs to load the native library.
  • Example:
    • 1.create java class - file ex1.java:
      • public class ex1 {publicnativeintfunct();static{System.loadLibrary("ex1.so");}}
      • #include ex1.hfunct() {...}
HTML version of Basic Foils prepared 22 February 97

Foil 5 Java - plug-ins communication

From Overview of TANGO Base Technology Rome Lab Quarterly Review for CIV -- October 1 96. *
Full HTML Index
Netscape provides netscape.plugin.Plugin class which is the Java representation of the native plug-in.Specific for particular plug-in subclass of java.plugin.Plugin must be created and installed together with plug-in itself (NPX_PLUGIN_PATH).LiveConnect mechanism automatically instantiates Java class representing plug-in.Communication between this object and the plug-in is done the same way as in general case of Java-native code communication, except for:
  • 1.different javah program is provided by Netscape (it must be run with additional parameter -jri) 2.one need not to explicitly load the native library - all code is in the plug-in dynamic library which is loaded automatically when necessary (Java object creation follows plug-in load).
HTML version of Basic Foils prepared 22 February 97

Foil 6 Java - JavaScript communication

From Overview of TANGO Base Technology Rome Lab Quarterly Review for CIV -- October 1 96. *
Full HTML Index
JavaScript defines hierarchy of objects on HTML page.These objects are accessible from Java via LiveConnect mechanisms implemented in netscape.javascript.JSObject class.
  • For example: JSObject.getWindow(this) method returns the root of the JavaScript hierarchy; JSObject.getWindow(this).getMember("document").getMember(frame_name) returns JSObject representing Netscape frame with parameter name=frame_name
  • For example: <script>package.class.method();</script>
HTML version of Basic Foils prepared 22 February 97

Foil 7 Applet - plug-in communication

From Overview of TANGO Base Technology Rome Lab Quarterly Review for CIV -- October 1 96. *
Full HTML Index
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