To Err is Human; To Correct, Complete

1. AgilityReboot:IV
To Err is Human;To Correct, Complete
Andrew Chum

2. In A Perfect, MagicalWorld…
• Whatever a client wants for software, a perfect software product will
appear.
• There is no software defects.
• Software requirements will never change.
• No need of any kind of software development framework or
methodologies.

3. To Err is Human
• Software Creation ProcessTimeline
• Requirements  Analyze  Software Requirement Specifications
(SRS)
• SRS  Design  Architectural Designs, Component Designs…
• Designs  Construct  Executables
• Executables  Verify  Releasable or not
• If theWorld is perfect, each phase produces perfect result and no
need to verify.
• In our imperfect world, human in each phase introduces mistakes.

4. To Correct, Complete
• It is well documented that defects identified later in SDLC are
expensive to fix than defects identified in early stage.
• To find out defects as early as possible.
• Since to err is human, each human activities for creating software
should be detected for errors.
• To Correct, Complete

5. How to minimize human error
• Prevention
• Detection
• Apply them to each development phase
• Requirements  Analyze w/ Prevention  SRS  Detection
• Incremental and Iterative

6. Prevention-Detection-Iteration
• Requirements  Analyze w/ Prevention  SRS  Detection
• SRS  Design w/ Prevention  Designs  Detection
• Designs  Construct w/ Prevention  Executables  Detection
• Executables  Verify  Releasable or not

7. Software Requirement Analysis
• Requirements  Analyze w/ Prevention  SRS  Detection
• Prevention
• Completeness, Consistency, Clarity,Testable,Traceable, Quantifiable …
• Detection
• Internal reviews
• Different levels of reviews: product management, development, testing, deployment
• External reviews with customers

8. Software Designs
• SRS  Design w/ Prevention  Designs  Detection
• Prevention
• Good Design Principles, Design Patterns, Control flow, Data flow, Module
Interfaces, Module Interactions, Scalability, Security, Fault-tolerance …
• Detection
• Infrastructure Framework, Simulations,Test Run…

9. Software Construction
• Designs  Construct w/ Prevention  Executables  Detection
• Prevention
• Coding Convention, ProgrammingTools, Static Analysis, Dynamic Analysis,
Resource Management, Performance, Scalability…
• Detection
• As complete as possible on test cases, UnitTests, IntegrationTests, System
Tests, ScalabilityTests, PerformanceTests,Test Automation, Automated
RandomTests…
• Detection 2: build-in monitoring for resources, performance,
traceability.

10. SoftwareVerification
• Executables  Verify  Releasable or not
• Put executables into production environment.
• Test with the same intensity as under Software Construction
Iterations.
• Pay attention to monitoring data which may reveal defects escaped
the testing.

11. Linear
Analyze Design Construct Verify

12. Linear Iterative
PreventionDetection
Design
PreventionDetection
Construct
PreventionDetection
Analyze
Monitoring
Verify

13. Overlapping
Iterative
PreventionDetection
Design PreventionDetection
Construct
PreventionDetection
Analyze
Monitoring
Verify

14. Incremental Iterative
• Outline &
Partition
• Sky
• Sea
• Rocks
• Coast
• Lighthouse
• Houses

15. Incremental Iterative
• Fill in more
details in
partitions

16. Incremental Iterative
• Fill in more
details & color
in partitions

17. Agility Essence
• To detect defects early
• Prevent defects in each human software activities
• Detect defects after each human software activities
• Incremental and Iterative

18. Q & A