An Xlet is very similar to a

Java applet Java applets were small applications written in the Java programming language, or another programming language that compiles to Java bytecode, and delivered to users in the form of Java bytecode. The user launched the Java applet from a ...

and is originally introduced in

Sun Microsystems Sun Microsystems, Inc. (Sun for short) was an American technology company that sold computers, computer components, software, and information technology services and created the Java programming language, the Solaris operating system, ZFS, th ...

Java TV Java TV is a Java-based software framework designed for use on TV set-top boxes, based on components called Xlets. It is currently used only on the Connected Device Configuration, specifically for iTV applications development. The API includes th ...

specification to support applications for

Digital TV Digital television (DTV) is the transmission of television signals using digital encoding, in contrast to the earlier analog television technology which used analog signals. At the time of its development it was considered an innovative advanc ...

. Though Xlet looks superficially different from other application models in Java such as applet and

MIDlet A MIDlet is an application that uses the Mobile Information Device Profile (MIDP) of the Connected Limited Device Configuration (CLDC) for the Java ME environment. Typical applications include games running on mobile devices and cell phones which ...

, it is actually meant to be a generalization of such models. The ''X'' in Xlet means an unknown, meaning that the Xlet framework may be used in any context rather than specific to Digital TV. Accordingly, Xlet was later re-introduced as a part of the Personal Basis Profile in the package, which is slightly different from the original design in the Java TV specification. The Xlet provision of a pause/resume feature is essential for a

set-top box A set-top box (STB), also colloquially known as a cable box and historically television decoder, is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of sign ...

(STB) environment, which has limited memory resources and restrictions on

bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...

from the head-end provider. The current practice and intent of the Xlet framework is to provide downloadable applications for Personal Basis Profile (PBP) platforms. In particular, the

BD-J BD-J, or Blu-ray Disc Java, is a specification supporting Java ME (specifically the Personal Basis Profile of the Connected Device Configuration or CDC) Xlets for advanced content on Blu-ray Disc and the Packaged Media profile of Globally Executab ...

platform uses Xlets as its programming framework. While Sun has provided a

reference implementation In the software development process, a reference implementation (or, less frequently, sample implementation or model implementation) is a program that implements all requirements from a corresponding specification. The reference implementation o ...

within which they provide a simple Xlet runner called RunXlet, at least one other open-source effort to implement an Xlet run has been made.XleTView
- an open-source project to implement a Java-based Xlet runner, also supporting Multimedia Home Platform (MHP) (not updated since 2004, based on JRE 1.1.8)

Code examples

The interface for an Xlet is defined in the javax.tv.xlet
/code> package: public interface Xlet thus an example of a stub Xlet is import javax.tv.xlet.XletStateChangeException; import javax.tv.xlet.XletContext; import javax.tv.xlet.Xlet; public class BasicXlet implements Xlet

Notes

{{Java (Sun) Interactive television Java device platform Articles with example Java code