chapter19 rapid application development
TRANSCRIPT
Copyright 2002 Prentice-Hall, Inc.
Modern Systems Analysisand Design
Third Edition
Jeffrey A. Hoffer Joey F. George
Joseph S. Valacich
Chapter 19Rapid Application Development
19.1
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
Discuss the conceptual pillars that support the RAD approach
Explain the advantages and disadvantages of RAD as an exclusive systems development methodology
19.2
Rapid Applications Development (RAD)
Systems development methodology created to radically decrease the time needed to design and implement information systems radically.Five key factors
1. Extensive user involvement2. Joint Application Design sessions3. Prototyping4. Integrated CASE tools5. Code generators
19.3
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 quickly
Traditional SDLC steps are followed, but phases are combinedIteration is limited to design and development phases
19.4
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
19.5
Approaches to RADMartin’s pillars of RAD Four pillars
Tools People Methodology Management
Conversion to RAD within organization should be done with a small group of well-trained and dedicated professionals, called a RAD cell
Over time, cell can grow until RAD is the predominant approach of the information systems unit
19.6
Approaches to RAD
McConnell’s pillars of RAD Four pillars
Avoid classic mistakes Apply development fundamentals Manage risks to avoid catastrophic setbacks Apply schedule-oriented practices
Table 19-1 lists some of McConnell’s 36 classic development mistakes
19.7
Approaches to RAD
McConnell’s pillars of RAD (continued) Development mistakes
Weak personnel Employees that are not as well trained in skills necessary
for success of the project Silver-bullet syndrome
Occurs when developers believe that a new and untried technology is all that is needed to cure the ills of any development project
Feature creep More and more features are added to a system over
course of development Requirements gold-plating
Project may have more requirements than needed19.8
Approaches to RAD
Software tools Case tools can be used for
Prototyping Code generation Example: COOL:Gen
Visual Development Environments Visual Basic Delphi
19.9
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
19.10
RAD Success StoriesInprise/Borland’s Delphi U.S. Navy Fleet Modernization
Requirements Move from three character-based systems to a unified,
GUI-based system based on a single database Reasons for choosing Delphi
Support for rapid prototyping Promise of re-use of components
Outcome System developed in 6 months Estimated development savings of 50 percent New system resulted in immediate 20 percent savings due
to reduced maintenance costs
19.11
RAD Success Stories
Inprise/Borland’s Delphi (continued) First National Bank of Chicago
Electronic Federal Tax Payment System Delphi enabled rapid prototyping and
development 10 months of development time 125 programmers 250 million rows of data and 55 gigabytes of
data on-line
19.12
RAD Success StoriesVisualAge for Java Comdata
Modular Over the Road System (MOTRS) IBM Global Services chosen as vendor Servlets
Programming modules that expand the functions of the Web server
Applets Embedded code run from client browser
Nine months to completion Three months of research Three months of coding Three months of testing
19.13
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
19.14
SummaryRapid Application Development Approach (RAD)
Components of RAD
Conceptual pillars that support RAD
RAD success stories
Advantages and Disadvantages of RAD
19.15