Devices

Java^TM software runs in many places, on many kinds of computers and consumer devices. Here's how it works on a Internet-ready screen phone with PersonalJava^TM technology:

	Java software is usually delivered automatically over a phone line, or can also be built into the phone. Examples of applications are phone directories, calendars, shopping services. Some applications will interact with a back-end server, so that software on the phone is kept small and light.
	A screen display engine1 provides the visible interface, and interacts with the Java virtual machine* (below).
	The Java virtual machine runs the software, after first doing stringent security checks. Often, the Java virtual machine is integrated directly into the phone's real time operating system (below).
	The phones's real-time operating system2 provides device-specific support for many of the actual operations and interactions.
	Result: Interactive Java software on your phone. Java software can also control the behind-the-scenes workings of the phone itself, and manage automatic software updates.

Back to: How the Java Platform Works

¹Actual design varies by phone make and model. Most phones will support both applications and applets, and will offer some kind of compact Web browser. An example of such a Web browser that will be licensed to device manufacturers is Sun's Personal Applications Browser.

²Telephones and other consumer devices use compact real-time operating systems that are produced by a number of different companies. The RTOS, Web browser, and other software are built into the phone or downloaded automatically (it's a simple model that's worlds away from today's complex computers!)

For a more detailed technical description of the workings of the Java platform, see The Java Language Environment - A White Paper.

*As used on this web site, the terms "Java virtual machine" or "JVM" mean a virtual machine for the Java platform.