© Prentice Hall 2002 9.1 CHAPTER 9 Application Development by Information Systems Professionals.

9.1

© Prentice Hall 2002

CHAPTER 9CHAPTER 9

Application Application Development by Development by

Information Systems Information Systems ProfessionalsProfessionals

9.2


SYSTEMS DEVELOPMENT SYSTEMS DEVELOPMENT LIFE CYCLE LIFE CYCLE (SDLC)(SDLC)

• DEFINITION PHASE: DEFINITION PHASE: – Feasibility analysis– Requirement definition

• CONSTRUCTION PHASE:CONSTRUCTION PHASE:– System design– System building– System testing

• IMPLEMENTATION PHASE:IMPLEMENTATION PHASE:– Installation– Operations– Maintenance

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9.3


DEFINITION PHASEDEFINITION PHASE

• FEASIBILITY ANALYSIS: FEASIBILITY ANALYSIS: Thorough Thorough analysis by team (leader, systems analysis by team (leader, systems analysts, end-users). Economic, analysts, end-users). Economic, operational, technicaloperational, technical

• REQUIREMENTS DEFINITION: REQUIREMENTS DEFINITION: If If feasibility report approved, team feasibility report approved, team develops logical design: processes, develops logical design: processes, data flow & relationships. Result is data flow & relationships. Result is system requirements documentsystem requirements document

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9.4


CONSTRUCTION PHASECONSTRUCTION PHASE

• SYSTEM DESIGN: SYSTEM DESIGN: Detailed design of Detailed design of physical system based on physical system based on requirements document. Details of requirements document. Details of hardware, software, databases, hardware, software, databases, modules, interrelationships for quality modules, interrelationships for quality system system (accurate, reliable, auditable, (accurate, reliable, auditable, robust, changeable, secure, efficient, robust, changeable, secure, efficient, user friendly, flexible, well user friendly, flexible, well documented)documented)

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9.5


CONSTRUCTION PHASECONSTRUCTION PHASE

• SYSTEM BUILDING: SYSTEM BUILDING: ISIS specialists specialists produce programs, databases. End-produce programs, databases. End-users answer questions, interpret users answer questions, interpret requirements, help design documentsrequirements, help design documents

• SYSTEM TESTING: SYSTEM TESTING: By module, By module, subsystem, entire system to find & subsystem, entire system to find & correct problems. Users acceptance testcorrect problems. Users acceptance test

• DOCUMENTATIONDOCUMENTATION

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9.6


IMPLEMENTATION PHASEIMPLEMENTATION PHASE

• INSTALLATION: INSTALLATION: Four strategiesFour strategies– Parallel: Run old & new systems for awhile to

check validity. Safe– Pilot: Install in one part of organization at a time.

Learn and adapt– Phased: In large system change one function at

a time (e.g., order entry)– Cutover: Start using entire system. Can be

dangerous if errors exist

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9.7


IMPLEMENTATION PHASEIMPLEMENTATION PHASE

• OPERATIONS: OPERATIONS: Training, documentation, Training, documentation, people and computers must work well people and computers must work well together. Project team disbandedtogether. Project team disbanded

• MAINTENANCE: MAINTENANCE: Operations stage of life Operations stage of life cycle. Correct errors as discovered, cycle. Correct errors as discovered, update as needed, monitor activities and update as needed, monitor activities and output. Be aware of gap between output. Be aware of gap between organization’s needs and system’s organization’s needs and system’s performanceperformance

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9.8


COST OF ERROR CORRECTIONCOST OF ERROR CORRECTION

3.51 10 20

50

150

0

50

100

150

200

1 2 3 4 5 6

PHASE IN WHICH ERROR DETECTED

RE

LA

TIV

E C

OS

T T

O

FIX

ER

RO

R

1. REQUIREMENTS 4. DEVELOPMENT TEST

2. DESIGN 5. ACCEPTANCE TEST

3. CODE 6. OPERATION

9.9


SDLCSDLC ROLES ROLES

• PROJECT MANAGER:PROJECT MANAGER: Must have Must have ISIS skills, plans skills, plans project, uses project management tools, builds project project, uses project management tools, builds project teamteam

• SYSTEMS ANALYST:SYSTEMS ANALYST: ISIS professional professional changes business problem into changes business problem into ISIS solution solution

• END-USER:END-USER: Functional representative Functional representative provides needs, judges resultsprovides needs, judges results

• SPONSORS, CHAMPIONS:SPONSORS, CHAMPIONS: Will be Will be addressed in Chapter 12addressed in Chapter 12

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9.10


SDLCSDLC CHARACTERISTICS CHARACTERISTICS

• MANAGEABLE PROJECT SIZE:MANAGEABLE PROJECT SIZE: Break into Break into independent pieces. Stay within budget & independent pieces. Stay within budget & other constraintsother constraints

• ACCURATE REQUIREMENTS ACCURATE REQUIREMENTS DEFINITION:DEFINITION: Extraneous specifications lead Extraneous specifications lead to added expense, extends completionto added expense, extends completion

• EXECUTIVE SPONSORSHIP:EXECUTIVE SPONSORSHIP: Sponsor with Sponsor with responsibility and resources critical to responsibility and resources critical to successsuccess

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9.11


SDLCSDLC ADVANTAGES ADVANTAGES

• HIGHLY STRUCTURED, HIGHLY STRUCTURED, SYSTEMATIC PROCESSSYSTEMATIC PROCESS

• THOROUGH DEFINITION THOROUGH DEFINITION REQUIREMENTSREQUIREMENTS

• CLEAR MILESTONES WITH CLEAR MILESTONES WITH MANAGEMENT SIGN-OFFSMANAGEMENT SIGN-OFFS

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9.12


SDLCSDLC DISADVANTAGES DISADVANTAGES

• MAY IGNORE EVOLVING MAY IGNORE EVOLVING REQUIREMENTS DURING REQUIREMENTS DURING PROJECTPROJECT

• TIME-CONSUMING, COSTLY TIME-CONSUMING, COSTLY PROCESSPROCESS

• TOP-DOWN COMMITMENT TOP-DOWN COMMITMENT REQUIREDREQUIRED

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9.13


PROTOTYPING LIFE PROTOTYPING LIFE CYCLECYCLE

11.. IDENTIFY REQUIREMENTSIDENTIFY REQUIREMENTS

2.2. DEVELOP INITIAL PROTOTYPEDEVELOP INITIAL PROTOTYPE

3.3. USE PROTOTYPE, NOTE CHANGESUSE PROTOTYPE, NOTE CHANGES

4.4. REVISE, ENHANCE PROTOTYPE: REVISE, ENHANCE PROTOTYPE: Return Return to Step 3 as neededto Step 3 as needed

5.5. EVALUATE OPERATIONAL SYSTEMEVALUATE OPERATIONAL SYSTEM

6.6. MAKE CHANGES OR ABANDONMAKE CHANGES OR ABANDON

7.7. INSTALL, OPERATE, MAINTAININSTALL, OPERATE, MAINTAIN

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9.14


COMBINING COMBINING PROTOTYPING & PROTOTYPING & SDLCSDLC

• PROTOTYPING/PILOTING PHASE:PROTOTYPING/PILOTING PHASE:– DETERMINE BASIC REQUIREMENTS

– PROTOTYPE SYSTEM

– PILOT PROTOTYPE

• SDLCSDLC CONSTRUCTION PHASE: CONSTRUCTION PHASE: – SYSTEM BUILDING

– SYSTEM TESTING

• SDLC SDLC IMPLEMENTATION PHASE:IMPLEMENTATION PHASE:– INSTALLATION

– OPERATIONS

– MAINTENANCE

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9.15


JOINT APPLICATION DESIGN JOINT APPLICATION DESIGN (JAD)(JAD)

• TECHNIQUE INVOLVING TEAM OF TECHNIQUE INVOLVING TEAM OF USERS, USERS, ISIS SPECIALISTS SPECIALISTS

• INTENSE, STRUCTURED PROCESSINTENSE, STRUCTURED PROCESS• DEVELOP REQUIREMENTS OR DEVELOP REQUIREMENTS OR

REVIEW DESIGN PROPOSALREVIEW DESIGN PROPOSAL• CAN LAST HOURS, DAYS, OFTEN AT CAN LAST HOURS, DAYS, OFTEN AT

LOCATION REMOVED FROM LOCATION REMOVED FROM WORKPLACEWORKPLACE

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9.16


COMPUTER-AIDED SOFTWARE COMPUTER-AIDED SOFTWARE ENGINEERING ENGINEERING (CASE)(CASE)

COLLECTION OF SOFTWARE TOOLS COLLECTION OF SOFTWARE TOOLS TO AUTOMATE TO AUTOMATE SDLC SDLC PROCESSES:PROCESSES:

• DIAGRAMMING TOOLSDIAGRAMMING TOOLS• COMPUTER DISPLAY, REPORT GENERATORSCOMPUTER DISPLAY, REPORT GENERATORS• ANALYSIS TOOLSANALYSIS TOOLS• CENTRAL REPOSITORYCENTRAL REPOSITORY• DOCUMENTATION GENERATORSDOCUMENTATION GENERATORS• CODE GENERATORSCODE GENERATORS

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9.17


RAPID APPLICATION RAPID APPLICATION DEVELOPMENT DEVELOPMENT (RAD)(RAD)

• HYBRID OF HYBRID OF SDLCSDLC, PROTOTYPING, , PROTOTYPING, JADJAD, , CASECASE

• PRODUCE SYSTEM IN 6 MONTHS OR PRODUCE SYSTEM IN 6 MONTHS OR LESSLESS

• STEPS:STEPS:– PLANNING – USER DESIGN – CONSTRUCTION– IMPLEMENTATION (CUTOVER)

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9.18


RADRAD ADVANTAGES ADVANTAGES

• DRAMATIC SAVING IN TIMEDRAMATIC SAVING IN TIME• FOCUSES ON ESSENTIAL FOCUSES ON ESSENTIAL

SYSTEM REQUIREMENTSSYSTEM REQUIREMENTS• ABILITY RAPIDLY TO CHANGE ABILITY RAPIDLY TO CHANGE

SYSTEM DESIGN AT USER’S SYSTEM DESIGN AT USER’S REQUESTREQUEST

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9.19


RADRAD DISADVANTAGES DISADVANTAGES

• QUALITY MAY BE SACRIFICED QUALITY MAY BE SACRIFICED FOR SPEEDFOR SPEED

• TIME CONSUMING FOR KEY TIME CONSUMING FOR KEY PERSONNELPERSONNEL

• POSSIBLE SHORTCUTS ON POSSIBLE SHORTCUTS ON INTERNAL STANDARDS, INTERNAL STANDARDS, MODULE REUSABILITYMODULE REUSABILITY

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9.20


OBJECT-ORIENTED OBJECT-ORIENTED METHODS METHODS (O-O)(O-O)

• HOLD GREAT PROMISE TO HOLD GREAT PROMISE TO PRODUCE BETTER SYSTEMS AT PRODUCE BETTER SYSTEMS AT LESS COSTLESS COST

• OBJECTS HIGHLY COHESIVE, OBJECTS HIGHLY COHESIVE, LOOSELY COUPLED, REUSABLE LOOSELY COUPLED, REUSABLE

• CAN REDUCE ERRORS, IMPROVE CAN REDUCE ERRORS, IMPROVE MAINTENANCEMAINTENANCE

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9.21


CHAPTER 9CHAPTER 9

Application Application Development by Development by

Information Systems Information Systems ProfessionalsProfessionals

© Prentice Hall 2002 9.1 CHAPTER 9 Application Development by Information Systems Professionals.

Documents

system design system

entire system

documented system design

large system

quality system accurate

prentice hall

logical design

technical feasibility