How Java Changed The Web
The
Internet helped catapult Java to the forefront of programming, and Java, in
turn, had a profound effect on the Internet. This how Java change 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. Let’s look more closely
at each of these.
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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, without further interaction with the user. If the user clicks a link
that contains an applet, the applet will be automatically downloaded and run in
the browser. Applets are intended to be small programs. They are typically used
to display data provided by the server, handle user input, or provide simple
functions, such as a loan calculator, that execute locally, rather than on the
server. In essence, the applet allows some functionality to be moved from the
server to the client. This is how java change the internet.
The creation of the applet
changed Internet programming because it expanded the universe of objects that
can move about freely in cyberspace. In general, there are two very broad
categories of objects that are transmitted between the server and the client:
passive information and dynamic, active programs. For example, when you read
your e-mail, you are viewing passive data. Even when you download a program,
the program’s code is still only passive data until you execute it. By
contrast, the applet is a dynamic, self-executing program. Such a program is an
active agent on the client computer, yet it is initiated by the server. As
desirable as dynamic, networked programs are, they also present serious
problems in the areas of security and portability. Obviously, a program that
downloads and executes automatically on the client computer must be prevented
from doing harm. It must also be able to run in a variety of different
environments and under different operating systems. As you will see, Java
solved these problems in an effective and elegant way. Let’s look a bit more
closely at each.
Security
Java
achieved this protection by confining an applet to the Java execution
environment and not allowing it access to other parts of the computer. (You
will see how this is accomplished shortly.) The ability to download applets
with confidence that no harm will be done and that no security will be breached
is considered by many to be the single most innovative aspect of Java.
Portability
Portability
is a major aspect of the Internet because there are many different types of
computers and operating systems connected to it. If a Java program were 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. As you will soon
see, the same mechanism that helps ensure security also helps create portability
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