Originally posted by Megha Jain:
JSp is easy as campared to servlets........ so why to go 4 servlets.....
That is where you are wrong.
JSPs may seem easier than servlets if you aren't comfortable with setting up your environment and running a compiler (which isn't all that hard).
Once past that hurdle, you will find servlets to be much more clear and straight forward. Their methods are well named and self descriptive.
They also haven't changed or grown much since their inception because there wasn't a need.
JSP (an abstraction meant to make it easier for non-programmer web designers to dress up the look and feel of a web app) hides and convolutes the structure of a servlet. They've grown and changed over the years. Features and ways to do things have been added but never removed. The result is 2 or 3 ways to express almost everything. Without a lot of discipline it would be extremely difficult a large project under one coding convention.
Each is an an excellent tool (as is the JavaBean) for it's intended purpose.
Together, the three provide the best platform (in my humble opion) for creating scaleable and managable web application.
Learn how to use all three, and how to combine them in a Model View Controller (MVC) architecture and you will have answered your own question.