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The purpose of this module is to explain session tracking using hidden fields, and to compare a servlet with a JSP to accomplish the same objective.

Table of contents


This module is one in a collection of modules designed for teaching INEW 2338 Advanced Java (Web) at Austin Community College in Austin, TX. The purpose of this module is to explainsession tracking using hidden fields, and to compare a servlet with a JSP to accomplish the same objective.

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find and view the Figures and Listings while you are reading about them.


  • Figure 1 . The servlet user interface at startup.
  • Figure 2 . Browser display for Tom, Dick, and Harry.
  • Figure 3 . Hidden fields in the servlet output.


  • Listing 1 . Beginning of the servlet class.
  • Listing 2 . Get and save the hidden values from the browser page.
  • Listing 3 . Get and save user input data.
  • Listing 4 . Begin constructing the HTML output data.
  • Listing 5 . Begin the HTML code for an HTML form.
  • Listing 6 . An input field and a submit button.
  • Listing 7 . Beginning of the list of names.
  • Listing 8 . Display the historical data and also save it on the browser.
  • Listing 9 . Display most recent value and also store it on the browser.
  • Listing 10 . Create basic web page structure.
  • Listing 11 . A JSP scriptlet.
  • Listing 12 . The body of the for loop.
  • Listing 13 . Another scriptlet.
  • Listing 14 . Another JSP expression tag.
  • Listing 15 . Terminating scriptlet and HTML code.
  • Listing 16 . The servlet program named Java4550a.java.
  • Listing 17 . The JSP program named Java4550a.jsp.

General background information

A stateless protocol

The HTTP protocol is a relatively simple request/response protocol that does not retain historical information from one client request to the next. In otherwords, each request is a new start insofar as the HTTP server is concerned. (HTTP is sometimes referred to as a "stateless" protocol.) However, historical information can be very important. The maintenance ofhistorical information is often referred to as "session tracking."

Session tracking

Session tracking is very important for many web applications including web commerce and web games. Therefore, this and the next several modules will show you some of the ways thatyou can accomplish session tracking using servlets and JSP.

Web commerce

Perhaps the most common example of the need for session tracking is with a web commerce application involving a shopping cart. The customer (client) downloads various pages from a vendor catalog, selecting items, and placing themin a shopping cart. At some point, the customer decides either to purchase the items or abandon the shopping trip.

If the customer decides to purchase the items in the cart, the web application must have a record of all the items in the cart. Furthermore, thatrecord must be associated with that particular customer so that the sale can be consummated.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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