Реферат: Java Essay Research Paper Java is the

Java Essay, Research Paper

Java is the substance whose aroma is awakening the Internet community.

It is a new programming language developed by Sun Microsystems that has

much in common with the beverage that shares its name. It’s good, it’s

hot, and people know it around the world. Java (the programming language)

beats the other stuff hands down though, it’s free. Many have heard of

Java, yet few know what it is, or what it can do. It certainly has the

potential to become a part of our everyday lives, existing in our mobile

phones, televisions, and Internet browsers. If you are interested in your

future read on.

Java is still in its infancy stage, yet to fulfil its intended

purpose. Designed in 1990 as an embedded language for consumer

electronics, it was later discovered to be an ideal interface to the

Internet. In 1996, Netscape added Java support to its popular Navigator

Web browser. The Web began to stir from its static text coma as excited

programmers began to incorporate Java applications, “applets”, into their

Web pages.

An applet is like an application, but it doesn’t run stand-alone.

An applet must adhere to a set of conventions that allows it to run within

a Java-compatible browser. The technology is still evolving, and today,

most Java applets are simple animations, or user interactions. The future

is brighter, promising full-blown applications over the Internet; imagine

using Microsoft Office from your television. For now, though, those who

have experienced an applet may be left disappointed. A casual user is

unlikely to be impressed with scrolling text, or simple animations,

especially if they must pay for them with increased download times.

Behind the scenes, unbeknownst to them, truly amazing things are


A Java applet begins its life by being “called” by a Web page. To be

technologically correct, the applet is embedded in the Web page. The Web

browser then downloads the applet and runs it on your machine. If you

just missed the amazing part: it runs on your machine. How can a program

from an unknown source be trusted to run on your computer without your

permission? It can’t unless that program was created using a secure

language like Java, and then wrapped with a secure viewing browser like

Netscape Navigator. The concept of being able to run applications on your

system is significant for several reasons. If you want to see a picture,

but don’t have a picture viewer, you can get both at once. This

eliminates the problem of not having the correct helper application or

even worse: having to settle for what’s available. The ability to run

applications on your system has another significant advantage.

Traditionally when you view something that “runs” on a Web page, or is

interactive, the work takes place on the remote computer, not yours.

Java frees Internet resources, allowing the work to take place on the

client’s system rather than the server’s.

If all applications were run on remote computers, the servers would be

inundated with traffic, and these collectively would propagate to bring

the entire Internet to a grinding halt. With a growing Internet

population, the prospect of this is real. There is a better way. If it

can be done safely, isn’t it quicker, not to mention more considerate, to

get what you need, take it with you, and use it on your time? A good

analogy is a long bank queue, with everyone waiting for the person in

front of them to finish. Some will be quick, and others will attempt a

hostile takeover on your lunch hour. Imagine a different world where

tellers were issued at the bank. Instead of waiting for a teller to

become free, you could simply take the teller you require from an almost

endless supply, then complete your transaction without delaying the people

behind you. You would only have to wait in line to get a teller. If the

bank got hundreds of new customers every day, would there be any other way

to do it? The issue of security would still have to be addressed. Away

from the work environment, how could you trust the teller you got? The

bank manager wouldn’t be around to oversee her. You would have to put her

in a sandbox.

A sandbox is the name given to the concept of setting the

boundaries in which a Java applet can “play”. A Java applet cannot look

at arbitrary files on the machine it’s running on, or have unauthorized

access to system resources. It can’t introduce a virus or other malicious

logic, delete critical files, or gain access to your passwords unless you

allow it to. It is security measures like the sandbox that make Java much

more than just a new programming language. Meet Java, the run-time


If Java were just another programming language, the industry would have

greeted its introduction with a resounding yawn. What makes Java

intriguing is that it is also a runtime environment embodied in what is

called a virtual machine (VM). This VM sits, in essence, between the Java

program and the machine it is running on, offering the program an abstract

computer that executes the Java code and guarantees certain behaviors

regardless of the underlying hardware or software platform. Java compilers

thus turn Java programs not into language for a particular machine but

into a platform-neutral byte code that the machine-specific VM interprets

on the fly1. A Java compiler is like a translator who translates a

language to a common ground like English. Since English is known around

the world, specific translators, like the VM, are able to translate

English into the language specific for their country. With so many

different computers connected to the Internet, platform independence is


Java has been thrust into the spotlight with its new language built on the

core values of security and platform independence. Sun Microsystems has

promised a “Write once, run anywhere” language suited to an Internet

community comprised of a smorgasbord of different computer, hardware, and

software configurations. The power to write programs that run on most

everyone’s computer is revolutionary. For Internet applications, though,

the value of platform independence degrades exponentially without strict,

built-in security. Java provides this security, and has the power to

change the way we compute.

1 PC Magazine: Your Guide to Java for 1998 — Your Guide to Java for 1998 4/7/98

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