INTRODUCTION TO JSP,JSP LIFE CYCLE, ANATOMY OF JSP PAGE AND JSP PROCESSING

COURSE:WEB TECHNOLOGIES
INTRODUCTION TO JSP,JSP LIFE
CYCLE, ANATOMY OF JSP PAGE
AND JSP PROCESSING
By
AAQIB HUSSAIN
MODULE-III

2
Course outcome / Topic learning outcome
Name of the Topic covered Topic Learning Outcome Course Outcome
Introduction to
JSP,Anatomy of JSP page
and JSP Processing
Understand and apply
the methods of servlet
for request - response
paradigm.
Develop a server side web
application using servlets
for request-response
programming paradigm
List the course outcome / Topic outcome

3
Outcome achieved
Name of the topic: Introduction to JSP,Anatomy of JSP page
and JSP Processing
Students will be able to do:
1 Design the dynamic web pages using HTML and JSP
2

JAVA SERVER PAGES
Introduction to JSP:
• Besides servlets there exists one more java based
technology called JSP(Java Server Pages) to develop
web applications.
• JSP was developed by Sun Micro Systems to allow
server side development.JSP is a kind of scripting
language in which we can embed java code along
with HTML elements.
• JSP is textual document that describes how to create
a response object from a request object of a given

JAVA SERVER PAGES
In the processing of JSP include:
• A JSP page defines JSP page implementation class
that implements the javax.servlet interface.
• At the request time ,the request is made to JSP page
which will be delivered to the JSP page
implementation object for processing.
• In any web application a program on server processes
request and generate response by using default HTTP
protocol.

JSP LIFE CYCLE
In the processing of JSP include:
• The web server needs a JSP engine, i.e, a container to
process JSP pages. It resides inside the webserver.The
JSP container is responsible for intercepting requests
for JSP pages.
Compilation process of JSP page involves three steps:
• Parsing of JSP
• Turning JSP into servlet
• Compiling the servlet

JSP LIFE CYCLE
1.Translation-
demo.jsp page
is translated in
to Servlet
2.Compilation-
Servlet
demo_jsp.java
is created
3.Class Loading-
demo_ jsp.java
is loaded in to
demo_jsp.class
6.Request Processing-
Servlet demo_jsp.java
is executed using
service method
5.Initiaization-
Servlet demo_ljsp
is initialized
4.Instantiation-
Servlet
demo_jsp is
instantiated
7.Destroy-
Servlet
demo_jsp is
destroyed

Anatomy of
JSP
A JSP page is a web page with JSP elements for generating the parts that
differ for each request.

Anatomy of JSP
• JSP page is a combination of JSP element and template text.
• Template text can be any text which includes HTML, WML, XML, or
even plain text. it can be used with any markup language.
• Template text is always passed directly to the browser.
• When a JSP page request is processed, the template text and
dynamic content generated by the JSP elements are merged, and the
result is sent as the response to the browser.

JSP Processing
• A web server needs a servlet container to provide an interface to
servlets, the server needs a JSP container to process JSP pages.
• The JSP container is responsible for intercepting requests for JSP
pages.
• To process all JSP elements in the page, the container first turns the
JSP page into a servlet (known as the JSP page implementationclass).
• The template text is converted to println( ) statements similar to the
ones in the hand-coded servlet and all JSP elements are converted to
Java code that implements the corresponding dynamic behavior. The
container then compiles the servlet class.
• Converting the JSP page to a servlet and compiling the servlet form
the translation phase.

• The JSP container initiates the translation phase for a page
automatically when it receives the first request for the page. Since
the translation phase takes a bit of time, the first user to request a
JSP page notices a slight delay.
• The translation phase can also be initiated explicitly and is referred to
as pre-compilation of a JSP page.
• Pre-compiling a JSP page is a way to avoid hitting the first user with
this delay.
• The JSP container is also responsible for invoking the JSP page
implementation class (the generated servlet) to process each request
and generate the response. This is called the request processing
phase.

The two phases are illustrated in the
figure

• As long as the JSP page remains unchanged, any subsequent request
goes straight to the request processing phase (i.e., the container
simply executes the class file).
• When the JSP page is modified, it goes through the translation phase
again before entering the request processing phase.
• The JSP container is also responsible for invoking the JSP page
implementation class (the generated servlet) to process each request
and generate the response. This is called the request processing
phase.

JSP Declarations
• A JSP declaration declares one or more variables or methods that
one can use in Java code later in the JSP file.
• The JSP declaration tag is a piece of java code mainly used to declare
fields and methods
SYNTAX
<%! declaration; [ declaration; ]+ ... %>

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