Servlet Overview and Architecture
So far, you've looked at Java applets—where the Java runs in the user's browser—and Java applications—where the program runs in a standalone JVM. In this chapter, you'll learn about Java programs that are designed to run on the same machine as the Web server.
If a visitor to your Web site is to install a Java application, he must first obtain a JVM (possibly in Sun's Java Runtime Environment, or JRE). Then the user must download the application's installation package and run the installer. Although this process is relatively painless, it's still much more work than, say, running an applet.
You can simplify the process of installing applications by packaging them with a double-clickable installation program ...