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 Professional
JSP
By Brown, Burdick, Cokor, Falkner , Galbraith, Johnson, Kim,
Kochmer, Kristmundsson, Li, Malks, Nelson, Palmer, Sullivan,
Taylor, Timney, Tyagi, van Damme, Wilkinson
Chapter 6: Combining Servlets, JSP, and JavaBeans
As shown in Chapter 3, the use of Servlets allowed convenient
management of events and program flow, but cumbersome ability
to generate responses. Conversely in Chapter 4, the use of
JSP provided excellent definition of response pages but gave
maintenance concerns with scriptlets embedded in between HTML.
Chapter 5 introduced beans as a way of eliminating some of
that scriptlet code with easy yet powerful tags.
This chapter attempts to unite the three technologies (Servlets,
JSP, and beans) by blending the best of all three approaches.
This approach solves most of the above problems. When we add
custom tags in later chapters, we will complete the picture.
In this chapter we will:
- Introduce the popular Model-View-Controller
(MVC) architecture. In the development of Graphical User
Interfaces, the MVC design pattern has emerged as a popular
architecture for partitioning functionality.
- Explore the MVC architecture and apply
it to our time entry system. This useful but limited example
will also dramatize the importance of comprehensive frameworks
such as Struts, which is discussed in depth in Chapter 21.
- Take a look at some advanced topics
with Servlets and JSPs, such as HTTP Session Binding Events.
- Discuss some advanced techniques for
combining Servlets and JSP, including the use of event listeners.
The Model View Controller Architecture
Originating with Smalltalk designs, the MVC pattern partitions
functionality into three interacting components — the Model,
the View, and the Controller. You may ask why do you care?
Often it is not always apparent where in your design functionality
should reside. For example, is a piece of functionality better
served using a JSP, Servlet, or a bean? Writing out all
of your HTML from a bean is surely not the appropriate solution,
just as putting all your business logic in a JSP is not appropriate.
MVC is a design paradigm where each component easily and naturally
maps to our three main implementation technologies — beans,
JSP, and Servlets. The Components of an MVC Architecture At
a simple level, the components of MVC architecture interact
as shown below. The Model holds the data, the View retrieves
the data and generates a dynamic display, and the Controller
provides the logic processing layer and delegation to the Model
and View... ...Let's now look at each of the major components
of the MVC design pattern in turn. We'll look at what the component
provides, and how it can be organized.
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Excerpted from Professional JSP
by Brown et al Copyright ©2001 by Wrox Press Inc. Excerpted
by permission of
Wrox Press, Inc. All rights reserved. No part of this
excerpt may be reproduced or reprinted without permission in
writing from the publisher.
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