Session 02 Struts Framework Presentation v1.0

8/8/2019 Session 02 Struts Framework Presentation v1.0

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2007, Cognizant Technology Solutions. All Rights Reserved.The information contained herein is subject to change without notice.

C3: Protected

Struts Framework

Targeted at: Entry Level Trainees

Session 02: Understanding Struts Framework


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About the Author

Created By: Santhosh Perumal (126073)

Baskar Senguttuvan (136303)

Credential

Information:

Baskar - PMP, SEI Architect

Santhosh - SCJP, SCWCD, SCBCD Certified Professional

Version andDate:

STRUTS/PPT/0508/1.0


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Questions

Contacts

Reference

TryitOut

HandsonExercise

CodingStandards

TestYourUnderstanding

Tools

AWelcomeBreak

Icons Used

3


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Struts Framework Session 02:Overview

Introduction:

The struts open source framework was created to

make it easier for developers to build Web

applications based on the Java Servlet and Java

Server Pages (JSP) technologies. Like a building, a Web application must have a solid

foundation from which the rest of the structure can

grow. The struts framework provides developers with

a unified infrastructure upon which Internet

applications can be based.


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Struts Framework Session 02:Overview (Contd.)

The Struts framework was created by Craig R.

McClanahan and donated to the Apache Software

Foundation (ASF) in 2000. The struts framework is

one of many well-known and successful Apache

Jakarta projects. Others includes Ant, log4j, and

Tomcat.


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Struts Framework Session 02:Objective

Introduction:

After completing this session, you will be able to:

Describe MVC architecture

Explain Struts Core packages

Explain Struts implementation of MVC

Describe the overview of Struts Framework


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MVC Architecture

In the Model View Controller (Model 2) architecture, the

client request is first intercepted by a servlet, commonly

referred to as a controller servlet.

This servlet handles the initial processing of the request

and determines which JSP page to display next.

Client never sends a request directly to a JSP page in

the MVC architecture. This allows the servlet to perform

front-end processing, including authentication and

authorization, centralized logging.


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MVC Architecture (Contd.)

Once request processing gets completed, the servlet

directs the request to the appropriate JSP page. This

approach is illustrated in following figure:


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All enterprise data and the business logic to process the

data can be represented in the MODEL.

The VIEW can access the data through the model anddecide on how to present them to the client. The VIEW

must ensure that the presentation changes as and when

the MODEL changes.

The CONTROLLER can interact with the view and

convert the client actions into actions that are

understood and performed by the MODEL. The

CONTROLLER also decides on the next view to be

presented depending on the last client action and

results of the corresponding MODEL actions.


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Following diagram displays MVC Architecture


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Advantages of MVC architecture:

MVC architecture is suitable for a highly interactive system

that requires extensibility, maintainability, and multiple user

views.

MVC decouples presentation, user interaction, and system

model.

Presenting multiple views for multiple data sets is made easybecause of the decoupling. This also makes it much easier to

enable support for new types of clients.

Code duplication is minimized by using this architecture.

By separating the presentation from model and overallapplication flow, this architecture enables division of

developer responsibilities and thereby, produces faster time

to market.


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What is a Framework?

A framework is a set of classes and interfaces that

operates to solve a specific type of software problem. A

framework has the following characteristics:

A framework comprises multiple classes or components,

each of which may provide an abstraction of some

particular concept.

The framework defines how these abstractions work

together to solve a problem.

Framework components are reusable.

A framework organizes patterns at a higher level.

A good framework should provide generic behavior that

can be used by different types of applications.


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Struts Core Packages

The struts framework is divided into 8 core packages. Figure

shows the top-level packages and their dependencies within

the framework.


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Struts Core Packages (Contd.)

Packagename

Description

action

Contains the controller classes, the ActionForm,ActionMessages, and several other required

framework components.

actions

Contains the "out-of-box" Action classes, such as

DispatchAction, that can be used or extended byyour application.

config

Includes the configuration classes that are in-memory representations of the Struts configuration

file.

taglibContains the tag handler classes for the Struts taglibraries.


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Struts Core Packages (Contd.)

Packagename

Description

tiles Contains the classes used by the Tiles framework.

upload

Includes classes used for uploading and

downloading files from the local filesystem, using

a browser.

utilContains general-purpose utility classes used by

the entire framework.

validator

Contains the Struts-specific extension classes used

by Struts when deploying the validator. Theactual Validator classes and interfaces are in the

commons package, separate from Struts.


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Struts Implementation of MVC

View layer Controller layer Model layer

Struts-

html.tld

Struts-

bean.tld

Struts-

logic.tld

ActionForwards

ActionForm classes

ActionMappings

ActionServlet

Action classes

ActionErrors

MessageResources

GenericDataSource


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Struts Overview

Following graphic explains the struts overview


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Struts Workflow

1. A request comes in with a .doc extension, the container

maps it to the ActionServlet.

2. The ActionServlet acts like a front end controller anddispatches control to a RequestProcessor.

3. The RequestProcessor finds an action tag with a path

attribute that matches the incoming request.4. Then the RequestProcessor looks for a form-bean tag

that has a name attribute that matched the action tags

name attribute.

5. RequestProcessor instantiates a FormBean of the of

based on the type attribute.


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Struts Workflow (Contd.)

6. RequestProcessor calls populates the FormBeans fields

from the incoming request, then calls its reset method,

then its validate method.7. RequestProcessor instantiates an action based on the

action tags type attribute.

8. RequestProcessor calls the action's execute method,

which returns an ActionForward.

9. The RequestProcessor finds a matching

ActionForward first within the nested forward tags,

then from within the global-forwards tag.


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Q & A

Allow time for questions from participants


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Test Your Understanding

1. What is MVC pattern?

2. What are the advantages of MVC?

3. List out some of the view components of

Struts Framework.

4. List out some of the Controller component of

Struts Framework.

k


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Struts Framework Session 02:Summary

Struts, a Jakarta project hosted by Apache is a

framework for building Web applications based on the

MVC design pattern.

The framework, built upon standard technologies like

Java Servlets, JavaBeans, ResourceBundles.

View is responsible for a presentation view of thebusiness domain.

Controller is responsible for controlling the flow and

state of the user input.

Model is responsible for the business domain state

knowledge.

S k S i 02


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Struts Framework Session 02:Source

Programming Jakarta Struts, 2nd Edition

http://java.sun.com/developer/technicalArticles/J2EE/despat/

Disclaimer: Parts of the content of this course is based on the materials available from the Web sites andbooks listed above. The materials that can be accessed from linked sites are not maintained byCognizant Academy and we are not responsible for the contents thereof. All trademarks, service marks,and trade names in this course are the marks of the respective owner(s).

Session 02 Struts Framework Presentation v1.0

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