Copyright 2004 Prentice-Hall, Inc.

Essentials ofSystems Analysis and Design

Second EditionJoseph S. Valacich

Joey F. GeorgeJeffrey A. Hoffer

Appendix BRapid Application Development

and CASE Tools

B.1B.1

Learning ObjectivesExplain the Rapid Application Development

(RAD) approach and how it differs from traditional approaches to information systems development

Describe the systems development components essential to RAD

Describe the typical components of a comprehensive CASE environment

Describe how CASE tools can be used to support RAD

B.2B.2

Learning ObjectivesDescribe visual and emerging development

tools and how they can be used to support RAD

Discuss the conceptual pillars that support the RAD approach

Explain the advantages and disadvantages of RAD as an exclusive systems development methodology

B.3B.3

Rapid Application Development (RAD)

Systems development methodology created to decrease the time needed to design and implement information systems radically.

Five key factors1. Extensive user involvement

2. Joint Application Design sessions

3. Prototyping

4. Integrated CASE tools

5. Code generators

B.4B.4

The Process of Developing an Application Rapidly

RAD is a general strategy rather than a single methodologyGoals

To analyze a business process rapidly To design a viable system solution through intense

cooperation between users and developers To get the finished application into the hands of

the users quicklyTraditional SDLC steps are followed, but phases are combinedIteration is limited to design and development phases

B.5B.5

B.6B.6

Components of RADUser involvement is key to success

Prototyping is conducted in sessions similar to Joint Application Design (JAD)

Prototyping screens become screens within the production system

CASE tools are used to design the prototypes

B.7B.7

CASE and Visual Development Environments

Computer-aided Software Engineering (CASE)

Software tools that provide automated support for some portion of the systems development process

Upper CASE CASE tools designed to support systems planning and

selection, systems analysis, and systems design phases of the systems development life cycle

Lower CASE CASE tools designed to support the systems

implementation and operation phase of the systems development life cycle

B.8B.8

CASE and Visual Development Environments

Cross life cycle CASE CASE tools designed to support activities

that occur across multiple phases of the systems development life cycle

Most CASE tools utilize a repository to store all diagrams, forms, models and report definitions

B.9B.9

B.10B.10

CASE and Visual Development EnvironmentsTypes of CASE tools Diagramming tools Computer display and report generators Analysis tools used to check for incomplete,

inconsistent or incorrect specifications A central repository Documentation generators Code generators

Form and report generators CASE tools that support the creation of system

forms and reports in order to prototype how systems will look and feel to users

B.11B.11

CASE and Visual Development EnvironmentsCode Generators CASE tools that enable the automatic

generation of program and database definition code directly from the design documents, diagrams, forms and reports stored in the repository

B.12B.12

Approaches to RAD

James Martin’s pillars of RAD Tools People Methodology Management

B.13B.13

B.14B.14

Approaches to RAD

Software Tools Case tools can be used for

Prototyping Code generation

B.15B.15

Approaches to RADMartin’s RAD Life Cycle Systems requirement determination is done in context

of a discussion of business problems and business areas

User Design End users and IS professionals participate in JAD workshops CASE tools are used to support prototyping

Construction Designer creates code using code generator End user validates screens and other aspects of design

Cutover New system is delivered to end users

B.16B.16

B.17B.17

B.18B.18

Advantages DisadvantagesDramatic time savings the systems development effort

More speed and lower cost may lead to lower overall system quality

Can save time, money and human effort

Danger of misalignment of system developed via RAD with the business due to missing information

Tighter fit between user requirements and system specifications

May have inconsistent internal designs within and across systems

Works especially well where speed of development is important

Possible violation of programming standards related to inconsistent naming conventions and inconsistent documentation

Ability to rapidly change system design as demanded by users

Difficulty with module reuse for future systems

System optimized for users involved in RAD process

Lack of scalability designed into system

Concentrates on essential system elements from user viewpoint

Lack of attention to later systems administration built into system

Strong user stake and ownership of system

High cost of commitment on the part of key user personnel

SummaryRapid Application Development Approach (RAD)

Components of RAD

CASE Tools

Visual Environments

Conceptual pillars that support RAD

Advantages and Disadvantages of RAD

B.19B.19