02_Designing JavaEE Applications

8/14/2019 02_Designing JavaEE Applications

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2Copyright 2007, Oracle. All rights reserved.

Designing Java EE Applications


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2-2 Copyright 2007, Oracle. All rights reserved.

Objectives

After completing this lesson, you should be able to do

the following:

Identify Java EE design patterns and their purpose

Describe the Model-View-Controller (MVC)architecture

Define the purpose and role of Struts

Define the purpose and role of JavaServer Faces

(JSF)

Define the Oracle Application Development

Framework


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Realizing Benefits of Java EE

To leverage the full benefits of Java EE, you must

design applications that are:

Portable: You should be able to redeploy the JavaEE applications to different servers, databases,and so on.

Scalable: Web applications should be able tohandle large numbers of users.

Maintainable: A minimum amount of codingshould be necessary for a new business rule.

Reusable: For example, a class that processescredit cards should be reused by multipleapplications.

Simple: The business need should be solved withthe least amount of complexity.


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Java EE Issues

It is important to follow certain guidelines for the

design and development of any new technology:

Implement generally accepted design patterns and

architectures. Focus on real business needs rather than simply

adopting new technology.

Employ the simplest technology to solve a

business problem.


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Java EE Design Patterns

Recurring application development issues have led to

the acceptance of design patterns. The generally

accepted design patterns include (but are not limited

to) the following:

Presentation-tier patterns

Intercepting filter

Controller servlet (as used in MVC)

Business-tier patterns

Data Access Object

Data Transfer Object


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The MVC Design Pattern

MVC is a framework that separately identifies the

components of an application as:

Business functionality (Model)

Presentation (View) Control logic (Controller)

View Controller

Model


7/222-7 Copyright 2007, Oracle. All rights reserved.

The Model

The model represents the enterprise data and

business rules that handle access and updates.

You can simplify the model by using two

mechanisms called facade class and commandpattern.

A facade encapsulates, hides the complexity of, and

coordinates the operations between cooperating

classes.

A command pattern encapsulates each applicationfunction in a separate class.

The model is often implemented using EJBs.



The View

The view focuses on presentation and is

responsible for maintaining consistency between

data presentation and model changes. It enables:

Presentation to be changed without altering

programming logic

Development by Web page authors having only

visual design skills

The view is commonly implemented using JSPs.



The Controller

The controller provides interaction with the client,

serving as a glue between the model and the

view.

The controller: Interprets user requests and controls businessobjects to fulfill these requests

Removes navigation coding from the view

Can be implemented in the client, Web, or EJB tier,

or in a combination of these tiers The controller is usually implemented as a servlet.

Struts and JSF are two widely used

implementations.



MVC in Oracle Application Server 10g

Containers for Java EE (OC4J)

Model updates Viewwhen data changes

View gets datafrom Model

Controller

Event is passed

to the Controller

Controller changesModel or View

Event

ViewView

Model



Struts: Overview

Struts is a framework for implementing the MVC

design pattern in Java EE applications.

Struts:

Is an open-source project from the ApacheSoftware Foundation

Is implemented by an XML-driven controller

servlet

Uses standard Java EE Web technologies

servlets, JSPs, and tag libraries

Can be used with other view-layer technologies:

Tiles: Page layout mechanism using JSP templates

Velocity: Page templating



Struts Components

Action Servlet: Part of the controller that receives

user inputs, and state changes and issues view

selections

Action: Part of the controller that interacts with themodel to execute a state change or query

Form Beans: Data (from forms) bundled into

JavaBeans for reuse and validation

Action Forward: Stores the path to a page where

the user is sent Action Mapping: Tells the servlet how each

request URI is mapped to an Action

Struts-config.xml: Contains the definitions ofthe Struts components used in an application



Struts Page Flow Design

Use the Struts Page Flow Diagram to create the

top-level page flow design of a Struts application:



JSF: Overview

JavaServer Faces (JSF) provides the same benefits as

the Struts architecture, including:

Controller servlet (MVC implementation)

Declarative and visual design in JDeveloper

XML configuration file (faces-config.xml)


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Oracle ADF Implementation

Model

ADF Business Components

TopLink Java Objects

EJBs Web services

Controller

Struts or JSF

View

JSPs, JSF pages, or ADF Swing



Oracle WebCenter Suite

Is an integrated technology suite comprising:

JavaServer Faces

Portal

Web 2.0 services Provides the ability to build applications that

enable users to interact directly with services such

as:

Instant messaging

Voice over IP

Discussion forums

Wiki services



Summary

In this lesson, you should have learned how to:

Identify Java EE design patterns and their purpose

Describe the Model-View-Controller (MVC)

architecture Define the role of Struts in an MVC framework

Define the role of JSF in an MVC framework

Describe how Oracle Application Development

Framework implements Java EEs best practices



Practice Overview:

Identifying MVC components

This practice covers the following topics:

Running the course application

Creating an application with two projects

Creating a database connection to access theSRDEMO schema


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02_Designing JavaEE Applications

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