java’s Contribution to Internet

The internet helped catapult Java to the forefront of programming, and Java, in turn, had a profound effect on the internet. In addition to simplifying web programming in general, Java innovated a new type of networked program called the applet that changed the way the online world thought about content. Java also addressed some of the thorniest issues associated with the Internet: portability and security.
Portability:  Portability is a major aspect of the Internet because there are many different types of computer and the operating system connected to it. If a java program is to be run on virtually any computer connected to the Internet, there needed to be some way to enable that program to execute on different systems. For example, in the case of an applet, the same applet must be able to be downloaded and executed by the wide variety of CPUs, operating systems, and browsers connected to the Internet. It is not practical to have different versions of the applet for different computers. The same code must work on all computers. Therefore, some means of generating portable executable code was needed.
Security:   As we are likely aware, every time we download a normal programs or files, we are taking the risk, because the code we are downloading might contain a dangerous virus, Trojan horse or other harmful codes. These codes will be dangerous because it has gained unauthorized access to system resources. For example, a viruses program might gather private information, such as credit card numbers, bank account balances, and passwords, by searching the contents of your computer’s local file system. In order for java to enable applets to be downloaded and executed on the client computer safely, it was necessary to prevent and applet from launching such an attack.
Jaba achieved this protection by confining an applet to the Java execution environment and not allowing it access to other parts of the computer. The ability to download applets with confidence that no harm will be done and that no security will be breached may have been that single most innovative aspect of java.
Java Applets
An applet is a special kind of Java program that is designed to be transmitted over the Internet and automatically executed by a Java-compatible Web browser. Furthermore, an applet is downloaded on demand, just like an image, sound file, or video clip. The important difference is that an applet is an intelligent program, not just an animation or media file. In other words, an applet is a program that can react to user input and dynamically change—not just run the same animation or sound over and over.

As exciting as applets are, they would be nothing more than wishful thinking if Java were not able to address the two fundamental problems associated with them: security and portability. Before continuing, let’s define what these two terms mean relative to the Internet.