Introduction

This unit will deal with the following issues:

	As we know Java can be used to write independent, standalone applications and also can be used for applets
	that run on the client side of a web client-server system.

	But how many desktop applications do you know that are used by millions of users worldwide? Little isn't it? Did
	you ask yourself why? Why there is no such a magic desktop application that is being accessed by millions of
	users? The answer is simple, desktop applications have an access limitation of their nature; you can’t access
	the application if you cannot access the computer where the application was installed.

	In addition, all standalone applications have a grip of deployment and platform problems, therefore there was a
	great need for such application that is running across platforms and accessible to anyone with a browser. This is
	a web application.

	Early web systems had some interactivity, using the concept of web forms. Most web users will have been seen
	these online forms, when filling in personal details to log on to some system or perhaps to buy something over
	web.

	The HTML code to display a web form is run by the browser on the client. However, there is clearly a need to
	process the form information and perhaps store it.

Introduction

	In these early systems, this processing was done following a set of standard rule called CGI or Common
	Gateway Interface. But to build a truly powerful web application, you need Java. You need servlets. You need
	JSPs. Because plain old static HTML pages are so, well, 1999. Today’s users expect applications that are
	dynamic, interactive, and custom-tailored.

In the next several pages we are going to discuss the following points:

Introduction to web applications.

N-tier architectures.

Client-side technologies.

Serve-side technologies.

Overview of Servlet.

Overview of JSP.