Transcript Software Quality: Topics

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Software Quality Concepts
SWENET Module SQA1
Software Quality: Topics
 Defining
software quality
 Attributes of software quality
 Quality trade-offs
 Quality attributes in requirements definition
Software Quality
 What
–
–
is quality?
In general
In business
?
Definitions: Quality is...
 Quality
is fitness for use (J. Juran)
 Quality is the most profitable product line we have
(H. Geneen)
 Quality
is free (P. Crosby)
 Quality is compliance to a standard
(W.E. Perry)
 Quality
(R. Glass)
is a degree of excellence
Quality Concepts
 Cost
effective investment
 Relative / Absolute
–
–
Within a Context?
Cadillac versus Chevrolet
 Compared
–
to some standard
Measurement and analysis implied
 An
intangible
Definition: Software Quality
 What
is software quality?
 What are the attributes of quality for software?
This is high quality software because...
?
Software Quality Attributes
Portability
Efficiency
Reliability
Usability
Testability
Understandability
Modifiability
(Boehm, 1978)
Software Quality Attributes
Usability
Functionality
Performance
FURPS+
Reliability
Supportability
( Grady / Hewlett-Packard)
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Software Quality Attributes
Product Revision
Maintainability
Flexibility
Testability
Product Transition
Portability
Reusability
Interoperability
Product Operation
Correctness
Integrity
Reliability
Usability
Efficiency
(Cavanno and McCall, 1978)
Software Quality Attributes
Boehm
FURPS+
Usability
Reliability
Efficiency
Usability
Reliability
Performance
Functionality
Supportability
Portability
Testability
Understandability
Modifiability
Cavanno/McCall
Usability
Reliability
Efficiency
Correctness
Integrity
Maintainability
Portability
Testability
Flexibility
Reusability
Interoperability
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Trade-offs and Quality
 Software
engineers must make trade-offs on many
levels and quality is no exception
 Quality compromises include
–
–
Trade-off among quality attributes
Trade-off of quality for other factors
Discussion: What trade-offs (including
quality) might affect a choice to purchase one
of the following:
- Luxury sedan
- Low end compact
- Pick-up truck
Tradeoff Among Quality Attributes
 Attributes
–
often conflict
Ref Glass
Portability
Efficiency
Usability
Understandability
Trade-off of Quality for Other Factors
 Quality
–
competes with other demands
Short term vs. long term effects
Quality
Time
Cost