1. Rekayasa Perangkat Lunak
Software Quality

2. Outline of this presentation
Software Quality
Mc Call’s Triangle of Quality
Mc Call’s Software Quality Factors
Product Operation
Product Revision
Product Transition

3. McCall’s Triangle of Qualityb l y F e x T s P o r R u I p C c E f g U O D A N S V

4. McCall’s Triangle of Quality
Correctness
Traceability
Completeness
Reliability
Consistency
Accuracy
Efficiency
Error tolerance
Execution efficiency
Integrity
Storage efficiency
Access Control
Usability
Access Audit
McCall’s Triangle of Quality
Operability
Training
Maintainability
Communicativeness
Simplicity
Flexibility
Conciseness
Instrumentation
Testability
Self-descriptiveness
Expandability
Portability
Generality
Modularity
Reusability
SW independence
HW independence
Communication commonality
Interoperability
Data commonality

5. McCall’s Software Quality Factors (1)
Product Operation
Correctness
Reliability
Efficiency
Integrity
Usability 7

6. McCall’s Software Quality Factors (2)
Product Revision
Maintainability
Flexibility
Testability 7

7. McCall’s Software Quality Factors (3)
Product Transition
Portability
Reusability
Interoperability 7

8. McCall’s Software Quality Factors (4)
Product Operation
Correctness
satisfies a specification
ideal quality
established w.r.t. the requirements specification
absolute 8

9. McCall’s Software Quality Factors (5)
Product Operation
Reliability
performs with precision
statistical property
probability that software will operate as expected over a given period of time
relative 8

10. McCall’s Software Quality Factors (6)
Product Operation
Efficiency
utilization of system resources
Integrity
control of access by the unauthorized
Usability
effort required to learn, operate, etc.
ability of end-users to easily use software
extremely subjective 8

11. McCall’s Software Quality Factors (7)
Product Revision
Maintainability
effort required to correct 9

12. McCall’s Software Quality Factors (8)
Product Revision
Flexibility
effort required to modify
ability to add or modify functionality
addresses adaptive and perfective maintenance
problem: evolution of implementation is too easy
evolution should start at requirements or design 9

13. McCall’s Software Quality Factors (9)
Product Revision
Testability
effort required to test
ease of establishing desired properties
performed by formal analysis or testing
internal quality 9

14. McCall’s Software Quality Factors (10)
Product Transition
Portability
dependency on hardware and operating environments
ability to execute in new environments with minimal effort
may be planned for by isolating environment- dependent components
necessitated by the emergence of highly- distributed systems (e.g., the Internet)
an aspect of heterogeneity 10

15. McCall’s Software Quality Factors (11)
Product Transition
Reusability
degree to which program can be used in other applications
ability to construct new software from existing pieces
must be planned for
occurs at all levels: from people to process, from requirements to code
FAKULTAS TEKNOLOGI INFORMASI
REKAYASA PERANGKAT LUNAK – KP146 – 3 SKS – BAG 10 10

16. McCall’s Software Quality Factors (12)
Product Transition
Interoperability
effort required for 2 systems to communicate
ability of software (sub)systems to cooperate with others
easily integratable into larger systems
common techniques include APIs, plug-in protocols, etc. 10

17. Software Qualities
Qualities (a.k.a. “ilities”) are goals in the practice of software engineering
External vs. Internal qualities
Product vs. Process qualities

18. Software Quality External vs. Internal Quality
External qualities are visible to the user
reliability, efficiency, usability, etc
Internal qualities are the concern of developers
they help developers achieve external qualities
maintainability, testability, flexibility,etc

19. Software Quality Product vs. Process Qualities
Product qualities concern the developed artifacts
maintainability, understandability, performance
Process qualities deal with the development activity
products are developed through process
maintainability, productivity, timeliness

20. Software Quality Software Process Qualities
Process is reliable if it consistently leads to high- quality products
Process is robust if it can accommodate unanticipated changes in tools and environments
Process performance is productivity
Process is evolvable if it can accommodate new management and organizational techniques
Process is reusable if it can be applied across projects and organizations

21. Software Quality Qualities must be measurable
Assesing Software Qualities
Qualities must be measurable
Measurement requires that qualities be precisely defined
Improvement requires accurate measurement
Currently most qualities are informally defined and are difficult to assess

22. Software Quality
Software Engineering “Axioms”
Adding developers to a project will likely result in further delays and accumulated costs
Basic tension of software engineering
better, cheaper, faster — pick any two!
functionality, scalability, performance — pick any two!

23. Software Quality The longer a fault exists in software
Software Engineering “Axioms”
The longer a fault exists in software
the more costly it is to detect and correct
the less likely it is to be properly corrected
Up to 70% of all faults detected in large-scale software projects are introduced in requirements and design
detecting the causes of those faults early may reduce their resulting costs by a factor of 100 or more

24. Finished,
Questions?