iTV

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iTV

What is iTV?

iTV stands for the term interactive TeleVision. iTV usually is implemented on a client, in this case a TV, with an Xlet. What is an Xlet?

Several different standards bodies and companies set out to define ITV including HAVi, MHP, MVB, SUN's JCP, and etc. These standarrds bodies came up with the concept of a Xlet which isimilar to a MIDlet.

Basically the Xlet is similar to an applet of MIDlet in that its an application that can run in the iTV environment ro set box environment and has default methods that define pause, start, and destroy application. For example an HelloWorld Xlet might look like this:

import java.awt.*;
import java.awt.event.*;
import  javax.microedition.xlet;
public class XletButtonDemo implements ActionListener, Xlet {
    private Container rootContainer;
    private PPButton button;
    public XletButtonDemo() {
    }
    public void actionPerformed(ActionEvent e) {
	System.out.println("Button pressed");
    }
    public void initXlet(XletContext context) 
	throws XletStateChangeException {
	try { 
	    button = new PPButton("Hello World");
	    rootContainer = context.getContainer(); 
	    rootContainer.setLayout(new BorderLayout());
	    rootContainer.setLocation(0,0); 
	    rootContainer.add(button, 
			      BorderLayout.CENTER);
	    rootContainer.pack();
	} catch (Exception e) { 
	    e.printStackTrace();
	}    
}
    public void startXlet() 
	throws XletStateChangeException {
	// Make the container visible. This method calls 
	// the paint method. 
	rootContainer.setVisible(true);
    }
    public void pauseXlet() {
	rootContainer.setVisible(false);   
    }
    public void destroyXlet(boolean unconditional) 
	throws XletStateChangeException {
	rootContainer.remove(button);    
	button = null;
    }
}

One of the differences between iTV in J2ME and MIDP in J2ME is the use of PersonalJava classes such as AWT to generate the graphics seen by the viewer. This accomplished by using several higher level Profiles within J2ME which detail the classes the developer can find accessible on the iTV setbox or TV device.

iTV is not the only area that Xlets can be found, the other areas include telematics and higher level PDAs. In the iTV case there are added libaries from HAVi and MHP-MVB that allow the developer to enable interactive features in iTV such as PVR like TiVo and etc.

Resources

last edited (January 29, 2004) by BadAttitude, Number of views: 8225, Current Rev: 9 (Diff)

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