What an applet is reviewed

Java can be used for the creation of two different types of programs. Applications, which we covered last chapter, are full fledged programs which has full access to the resources of the computer. In fact, applications can even call native programs and access native libraries giving applications incredible power. Applets, which were designed to be used over the internet, and appear within the user's browser. Applets were intended to be a platform independent way of adding functionality to a web browser.

Applets are loaded on demand when the user goes to the web page that the applet is on. This obviously could pose potential security problems. Java handles these concerns by running the applet in what is known as a sandbox. The sandbox drastically restricts what the applet can do. Loading and saving files off of the users computer, as well as running programs and using native libraries is forbidden. Likewise, the applet is only able to communicate with the server from which it was loaded. This, and other restrictions, prevents the applet from doing any harm to the users machine.

Despite the restrictions that the sandbox presents, there are still advantages to using applets. The biggest advantage is that, despite the efforts of a certain Monopoly, applets are cross-platform capable. This means that the same applet will run on a Windows machine, a Linux machine, or a Macintosh. In fact, it will run on any machine that has a browser that is able to run Java applets.

In order to insure that the applet will run on the most browsers possible, I would recommend restricting your applets to the Java 1.1 standard. Even though JDK1.4 has been released, and has much more features than java 1.1, a certain monopoly is only including Java 1.1 with it's browsers. In fact, depending on the outcome of a court case that is currently in progress at the time I am writing this, Microsoft may be able to stop distributing Java period. This is one of the reasons that I have started to do more games using Macromedia's Flash.

Some of you are probably worried about having to learn how to program applets as well as applications. The truth is, that applets are really just applications with some restrictions and a few extra methods to allow the browser to better control the applet.