Managing Information Technology

Chapter 2 • Computer Systems 51

transactions, they all have the following things in

common:

1.All Web applications are based on an n-tier architec-

ture (where ). The typical system consists of

three tiers: a user interface (client), a Web or applica-

tion server, and a database server.

2.The user interacts with the system (on his or her ma-

chine) through Web-based forms. Data entered into

the forms are sent to the server, where a server appli-

cation program processes them. This program might

write parts of this information to a database (residing

on a different machine).

The most common user interface encountered by

users is an HTML form. This form might be either static

or dynamic (i.e., produced by a program). Languages used

to produce the form might run on the server side

(e.g., PHP) or the client side (e.g., JavaScript). Often

nÚ 2

public class AnimalTest

{

public static void main(String args[])

{

Animal myanimal;

myanimal = new Dog("10.5", 30,"Black");

myanimal.display();

}

}

FIGURE 2.13 Java Instantiation of a New Dog

public class Dog{

double height;

double weight;

String color;

public Dog (double someheight, double someweight, String somecolor)

{

height = sometype;

weight = someweight;

color = somecolor;

}

//methods

public void sleep() {

//code to make a dog sleep will go here

}

public void run() {

//code to make a dog run will go here

}

public Object fetch() {

//code to make a dog fetch will go here

//this method will return the item fetched

}

public void display()

{

System.out.println("The Height of Animal is: " + height);

System.out.println("The Weight of Animal is: " + weight);

System.out.println("The Color of the Animal is: " + color);

}

}

FIGURE 2.12 Java Class Called Dog

Languages for Developing Web Applications

Although Web-based applications range in complexity
from very simple applications that allow user regis-
tration to applications that enable business-to-business