Devices

Java software runs in many places, on many kinds of computers and devices. Here's how it works in a wireless phone with PersonalJava or EmbeddedJava technology:

	Java software can be built into the phone, or delivered in real time via a wireless connection. Examples of applications are stock quotes, calendars, and address books. 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 on the phone, 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 phone's real-time operating system2 provides device-specific support for many of the actual operations and interactions.
	Result: Interactive Java software integrated into the 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

¹The method for displaying Java applets and applications varies by make and model of phone. Large, full-featured phones may contain tiny Web browsers. Simpler models may have a basic applet viewer or display engine built in. Regardless of this internal architecture of the phone, though, the Java software itself is device-independent.

²Wireless phones and other consumer devices use compact real-time operating systems that are produced by a number of different companies. The RTOS, Web browser or screen display application, and other software are built into the phone or downloaded automatically (it's a simple model that 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.