Table of Contents
Reducing Uncertainty About Software Safety.(3 hour tutorial)
Outline
This Tutorial's Assessment Techniques
Reality Check
SoftwareQuality
So What is Software Quality?
Where Will We Get Quality?
Achieving vs. Assessing Quality
Our 30-Year "Quality-Seeking" Adventure
1. Process Improvement/Maturity
2. Formal Methods
3. Languages and OO Design
4. Code Measurement
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5. Software Development Standards
And So
So Where Have We Gotten To?
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So Where Have We Gotten To?
.
And Finally
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Software Testing
When Does Testing Begin?
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Definitions
Definitions
Definitions
Definitions
Oracle
Definitions
The Testing Process
Why Do We Test?
The "Reliability Assessment" Process
Why Do We Test?
The Great Myth: "Test-out" the Bugs
And So
Did You Know That:
Did You Know That:
Did You Know That:
Did You Know That:
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Did You Know That:
"Off the Record"
Testing's Main Theoretical.and Practical Problems
Testing Problem #1: Time
Problem #2: Faults Hide From Tests
Software that Always Fails
Correct Software
Typical Software
Fault Density (Fault Size)
Fault Density
ORs vs. ANDs
What Makes a Chain Longer?
Design-for-Testability (DFT)
Fault Density and Safety: Dichotomy
Can We Have It Both Ways?
Problem #3: Test Management/Costs
Problem #3: Test Management/Costs
Problem #4: What Techniques To Use?
Problem #5: When To Stop Testing?
Problem #6: What Tools to Use?
Problem #7: Training Personnel
Problem #8: Books and Education
Solution: Just Do More Testing, Right?
The "Assessment" Gap Grows
Today
.
Software Fault Injection
A Better Approach?
Software Fault-Injection
When Can Fault Injection Occur?
Two Types of Anomalies
Two Ways to Implement
Internal Anomaly State Spaces
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Five Key Points
Algorithm for Injecting.Internal Data Anomalies
Injecting Internal Data Anomalies
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PRED: Undesirable Software Outputs
Numerical Results from EPA
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Algorithms for Injecting.External Data Anomalies
Goal
Interface Propagation Analysis (IPA)
Estimating "Propagation Across"
Estimating "Propagation From"
Particularly Useful for Acquired Software
Specifically, Operating System Calls
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Mitigation Strategies
"Propagation From" Satisfies PRED?
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"Propagation Across" Satisfies PRED?
Other Types of Software .Applications That Can Benefit .from Fault Injection
Application #1: "Continuously Operating" Software
Questions of Interest
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Application #2: Component-Based System
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Questions of Interest
..
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Application #3: Firewall and Partition Testing
Case Studies
Case Studies from EPA Fault Injection
Bay Area Rapid Transit
UVA Prototype Magneto Stereotaxis System
Software hazards:
Halden. Nuclear. Reactor . Project
New Research:.Other "Non-Software" Applications
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Hazard Mining
Fault Injection Compliments
Inverted Distributions: Rare Inputs
Summary Points
Certifying Safe Behavior from Observations
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Conclusions
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