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Outline
• The waterfall life cycle model• The triangular life cycle model• Using the model to improve software
quality• Conclusion
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First..
…the waterfall life cycle model…
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ProjectManagement
TimeManagement
CostManagement
ScopeManagement
QualityManagement
…the waterfall life cycle model is based on…
…the project life cycle…
… and project management priorities
Initial FinalIntermediate
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There are many problems with the waterfall life cycle model
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Success, glory, promotion is mine at last!
Project Manager
Initial FinalIntermediate
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Ah ha! Project
contingency!
Project Manager
Testing
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The Triangular Life Cycle Model
Product vs. project life cycleQuality vs. project prioritiesViews of quality vs. Gantt charts
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NeedsWants
Expectations
NeedsWants
Expectations
The Product Life Cycle
Nothing is perfectNothing is finished
Nothing lasts
Product Product Opp
ortu
nity
Requ
irem
ent Wabi-Sabi
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ProjectManagement
TimeManagement
CostManagement
ScopeManagement
QualityManagement
Quality Management Priorities
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Value viewWhat the user is prepared to pay for quality
ExcellenceQuality can be recognised but not easily defined
User’s viewAbility to satisfy user’s needs
Manufacturer’s viewConforms to the specification
Product viewMeasurable aspect of the product
Views of Quality
ExcellenceQuality can be recognised but not easily defined
ExcellenceQuality can be recognised but not easily defined
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Need
Product
GapsBetween
the Views of Quality
Gap
GapG
ap
Spec
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The Reasons For Gaps
“Gap”
“Gap
”
Follow thespecification“Voice of the
process”
Understand the user’s needs“Voice of the
customer”
I’ll know it when I see it“IKIWISI”
“Gap”
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Product and
Process
Need Spec
Product
NeedsWants
Expectations
NeedsWants
Expectations
Product Product
Opp
ortu
nity
Opp
ortu
nity
Requ
irem
ent
Requ
irem
ent
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Product and
Process
Need Spec
Product
OperationDep
loymen
t
Construction
Desi
gn
Requirements
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The Triangular Life Cycle
Model
Need Spec
Product
Wabi-Sabi
Voice of the customer
Voice of the processIK
IWIS
I
OperationDep
loymen
t
Construction
Desi
gn
Requirements
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Closing the “Gaps”
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The Role of Verification
and Validation
Need Spec
Product
ValidationAre we building
the correct product?
VerificationAre we buildingthe product
correctly?
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Closing the Gaps With
Verification Unit testing
Integration testing
System testing
Source code review
Need Spec
Product
Design review
Architecturereview
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Closing the Gaps With
Requirements Validation
Workshops StakeholderreviewPrototypes
ModellingNeed Spec
Product
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Measuring the Final Gap With Product
ValidationPostimplementation
review
Need Spec
ProductAcceptance testing
Operational testing
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The Testing Region
Testing
region
Unit testing
Integration testing
System testingAcceptance testing
Product
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Closing the Gaps With
Configuration Management
IdentificationVersion control
Change control
Need Spec
Product
Requirements management
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Closing the Gaps With Configuration Management
Antic
ipated gap
Scope change
Actual ga
p
Spec
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Closing the Gaps With
Defect Prevention
Need Spec
Product
Defect injection
Defect removal
Correctiveaction
Defect injectionDefect injection
Defect removalDefect removal
Erroranalysis
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Closing the Gaps With
Rework
Need Spec
Product
Rework
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Closing the Gaps With Iteration
Iteration review
Iteration plan Need Spec
Product
Refinement
1.Prototype (LCO)2.Architectureproof of concept(LCA)3.Acceptancetest (IOC)
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Need Spec
ProductClosing the Gaps With Process
Improvement
Cost of poor quality
Cost ofclosingthe gaps
total quality budget = cost of poor quality + cost of closing the gaps
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Closing the Gaps With Process Improvement
Cos
t
Quality
Cost of closing the gaps
QualityBudget
Cost of poor quality
Increase the quality budget
Value view
Spending thequality budget more wisely
Construction
Desi
gn
Requirements
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Construction
Desi
gn
Requirements
Closing the Gaps With Process Improvement
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InvestmentReturn
Cos
t
Quality
Cost of closing the gaps
Closing the Gaps With Process Improvement
Cost of poor quality
QualityBudget
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“Triangular” Maturity Models
Communicate Misun
ders
tand
Ideal
Outsource
Hopeles
s
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Conclusion
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A question of balance…
Scop
e
Work Product
ActivitiesQua
lity Ti
me
Cos
t
Quality Management Priorities
Project Management Priorities
Need Spec
Product
Need Spec
Product
Wabi-Sabi
Voice of the customer
Voice of the process
IKIW
ISI
OperationDep
loymen
t
Construction
Desi
gn
Requirements
