One day, you may have a refrigerator that runs Java. What would that mean to you? Probably nothing, unless it makes you play Tetris in order to use the ice maker. The toaster has always been the appliance that everyone wants to connect to the Internet. Yes, someone has demonstrated a Java-enabled toaster. In fact, Sun has considered changing its trademark phrase "The Network Is The Computer" over to "The Toaster Is The Computer." Okay, not really. Still, if things continue in the direction they are going, you will have more and more pieces of equipment in your house that run Java. This can be upsetting to an application designer who is accustomed to thinking of the desktop as the sole realm of applications.

This is where the notion of separating the user interface from the application really becomes important. You can't cram some behemoth of an application into a cell phone. You shouldn't even try. Take the flight tracking system as an example.

Suppose the airline president handed you his Java-enabled organizer and said, "I want to see flights on this thing." Fortunately for you, you separated the application from the user interface, so all you have to do is create a special user interface for the organizer.If you had written the flight tracking system as a big stand-alone application, you would have already torn your hair out in big clumps trying to figure out how you were going to fit all that code into an itty-bitty living space.

You may, in the future, have a completely different computing model at home than you do now. Right now, you probably have a single computer, a printer, a monitor, and a modem. Some of you even have your own ethernet networks now. In the future, you may have an application server on which all your favorite programs reside-your e-mail system, your word processor, and yes, your favorite games. This server may not even have a keyboard or a monitor, just a connection to your home network. On your desktop, you might have a Java-enabled monitor and keyboard that are also hooked to the network. In the living room, your Java-enabled television is also on the network. With the coming of digital TV and high-speed networking to the home, there may no longer be a difference between a computer monitor and a television. When you want to read your e-mail, you can access it from the computer monitor, your TV, or even your wireless digital assistant, all using your home network to access the e-mail application running on your home server. You may not even have a server at home-you might subscribe to an e-mail service over the network and access a server somewhere in Tuscaloosa. The point is that there are more and more ways for you to interact with computer systems, and in the future, one single way will no longer be sufficient.