chapter 10 m ethodologies for c ustom s oftware d evelopment
DESCRIPTION
CHAPTER 10 M ETHODOLOGIES FOR C USTOM S OFTWARE D EVELOPMENT. S YSTEMS D EVELOPMENT L IFE C YCLE M ETHODOLOGY. Systems development life cycle (SDLC) – a highly structured approach for development of new customized software applications. Page 385. - PowerPoint PPT PresentationTRANSCRIPT
E. Wainright Martin Carol V. Brown Daniel W. DeHayesJeffrey A. Hoffer William C. Perkins
MANAGINGMANAGINGINFORMATIONINFORMATIONTECHNOLOGYTECHNOLOGY
FIFTH EDITION
CHAPTER 10
METHODOLOGIES FOR CUSTOM SOFTWARE DEVELOPMENT
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SYSTEMS DEVELOPMENT LIFE CYCLE METHODOLOGY
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Systems development life cycle (SDLC) – a highly structured approach for development of new customized software applications
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SYSTEMS DEVELOPMENT LIFE CYCLE METHODOLOGY
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The SDLC Steps
Figure 10.1 The Systems Development Life Cycle
Key characteristic is extensive formal reviews
required at end of each major step
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The SDLC Steps
Figure 10.2 Cost Breakdown for $1 Million SDLC Project
Hallmark of SDLC approach: extensive up-front time spent
determining requirements to avoid expensive changes later
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SYSTEMS DEVELOPMENT LIFE CYCLE METHODOLOGY
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The SDLC Steps
SDLC: Most often requires a lot of documentation Outputs from one step inputs to next Often referred to as the “waterfall” model
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Definition Phase – Feasibility Analysis
Types of feasibility – economic, operational, and technical
Deliverable – 10-20 page document: Executive overview and recommendations Description of what system would do and how it would operate Analysis of costs and benefits Development plan
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Definition Phase – Requirements Definition
Focuses on logical design: processes, data flows, and data interrelationships – not specific physical implementation
Deliverable – system requirements document: Detailed descriptions of inputs and outputs, processes used to convert
input data to outputs Formal diagrams and output layouts Revised cost/benefit analysis Revised plan for remainder of project
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Construction Phase
System Design
System Building
System Testing
Figure 10.3 Characteristics of High Quality Systems
Documentation is a major mechanism of
communication during development process
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Implementation Phase
Installation
Operations
Maintenance
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Implementation Phase – Installation
Figure 10.4 Implementation Strategies
Parallel Strategy
Cutover Strategy
Phasing Strategy
Pilot Strategy
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Implementation Phase – Maintenance
Figure 10.5 Percent of Development Resources Devoted to Maintenance
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Implementation Phase – Maintenance
Figure 10.6 The Widening Gap BetweenOrganization’s Needs and System’s Performance
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The SDLC Project Team
Usually temporary
Includes personnel from IS and business units
Has a project manager Traditionally from IS Can be from business unit May be one from each Responsible for success of project – delivering quality system on
time and within budget
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SYSTEMS DEVELOPMENT LIFE CYCLE METHODOLOGY
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The SDLC Project Team
Includes systems analysts Have critical roles Work closely with business managers and end users Have problem-solving skills, knowledge of IT
capabilities, strong business understanding
Has a business sponsor and a champion
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Managing an SDLC Project
Characteristics critical for success: Manageable project size Accurate requirements definition Executive sponsorship
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Managing an SDLC Project
(Adapted from Boehm, 1976)
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SDLC Advantages and Disadvantages
Figure 10.8 Advantages and Disadvantages of Traditional SDLC Approach
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PROTOTYPING METHODOLOGY
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Prototyping approach: Takes advantage of availability of fourth generation
procedural languages and relational database management systems
Enables creation of system (or part of system) more quickly, then revise after users have tried it
Is a type of evolutionary development process
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PROTOTYPING METHODOLOGY
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Prototyping examples: Input and output screens developed for users to test as part of
requirements definition
“First-of-a-series” – a completely operational prototype used as a pilot
“Selected features” – only some essential features included in prototype, more added later
Prototyping used as a complete alternative to traditional SDLC methodology
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PROTOTYPING METHODOLOGY
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Prototyping used as a complete alternative to traditional SDLC methodology:
Good when requirements hard to define
Good when system needed quickly
Impractical for large, complex applications
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The Prototyping Steps
Figure 10.9 The Prototyping Life Cycle
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PROTOTYPING METHODOLOGY
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Representatives from IS and user management necessary
Need team members who can quickly build systems using advanced tools
Requires dedicated business user roles
The Prototyping Project Team
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PROTOTYPING METHODOLOGY
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Advantages: Only basic requirements needed at front end
Used to develop systems that radically change how work is done, so users can evaluate
Allows firms to explore use of new technology
Working system available for testing more quickly
Less strong top-down commitment needed at front end
Costs and benefits can be derived after experience with initial prototype
Initial user acceptance likely higher
Prototyping Advantages and Disadvantages
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Disadvantages: End prototype often lacks security and control features
May not undergo as rigorous testing
Final documentation may be less complete
More difficult to manage user expectations
Prototyping Advantages and Disadvantages
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Prototyping within an SDLC Process
Figure 10.10 SDLC with Prototyping to Define Requirements
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Prototyping within an SDLC Process
Figure 10.11 Prototyping/Piloting Replaces SDLC Definition Phase
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NEWER APPROACHES
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Rapid Application Development (RAD)
Figure 10.12 Four-Step RAD Cycle
Hybrid methodology – aspects of SDLC and prototyping
Goal is to produce a system in less than a year
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Rapid Application Development (RAD)
Joint application design (JAD) – a technique in which a team of users and IS specialists engage in an intense and structured process in order to minimize the total time required for gathering information from multiple participants
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NEWER APPROACHES
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Rapid Application Development (RAD)
Joint application design (JAD) – a technique in which a team of users and IS specialists engage in an intense and structured process in order to minimize the total time required for gathering information from multiple participants
Computer-aided software engineering (CASE) – any software tool used to automate one or more steps of a software development methodology
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NEWER APPROACHES
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Rapid Application Development (RAD)
Figure 10.13 Types of CASE Tools
(Adapted from Valacich, George, and Hoffer, 2001)
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NEWER APPROACHES
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Rapid Application Development (RAD)
Figure 10.14 RAD Advantages and Disadvantages
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Agile Software Development Discipline
Alternative methodology for smaller projects
Based on four key values: Simplicity Communication Feedback Courage
One type: Extreme Programming (XP) Programmers write code in pairs Use simple design and frequent testing
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MANAGING SOFTWARE PROJECTS USING OUTSOURCED STAFF
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Advantages: Helps keep software development costs down Uses technical expertise not available in-house Can often complete projects more quickly
Off-site outsourcing: Onshore – within same country or region Offshore – not within same country or region
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Offshore alternative good option when: System requirements well-defined and remain stable Time is of essence and 7x24 hour availability of
resources a good idea Cost of project important
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Guidelines for managing offsite outsourcer: Manage expectations, not staff Take explicit actions to integrate the offsite workers Communicate frequently Abandoning informal ways may result in increased
rigor