Tradeoff Analysis of Strategies
for System Qualities
Xuan Zhang
YNU Visiting Scholar
3/15/2016
SQs and NFRs
• System qualities (SQs) are impacted by nonfunctional requirements (NFRs).
• NFRs state “how well” while FRs state “what”
NFRs=how well (FRs)
• Design state “how” the system should
perform the functions.
– Developing to the design will satisfy FRs and NFRs.
Strategies
• The need for a particular SQ
– use specific strategies to optimize the system for
this SQ
• improve the particular SQs
• may hurt other SQs.
• Systems increase in diversity and complexity,
the strategy alternatives for SQs constitute a
vast space of options.
Strategies
• Redundancy Design
– Reliability, Safety, Maintainability
– Security, Speed
• Fault-tolerant Design
– Reliability, Usability
– Security, Accuracy
• Encryption Design
– Security
– Speed, Maintainability
• End-user Programming, Across domain
component, Tight Coupling.....
Zhu’s Tradeoff Analysis
My Tradeoff Analysis
Optimize Tradeoff
SQs Tradeoff Framework
SQs Priority
Synergies and Conflicts
Tradeoff Optimization
Impact of Changes
3 Categories of Strategies
COCOMO II
Agile method may
be risky in security,
reliability, safety.
COCOMO Strategies
Measurable Strategies
Tradeoff Summary
High Level Architecture
Support Tool
Screen1: SQs Priority Ranking
COCOMO II
Screen2: Strategy management
Accuracy priority is low.
Using in security critical
components is risky.
Screen5: Strategy solutions management
Screen4: Strategy solutions management
标题改为Conflict SQs
Conflict SQs
Security
Speed
Screen7: Strategy tradeoff
Solutions
Solutions
Minimum
baseline
Constraints
Maximum
baseline
Back
Analysis
Exit
Screen6: Strategy tradeoff
改为Tradeoff
comments
C1
C2
C3
C4
C5
Values
Empirical Application
• A trusted third party certification authority
(CA) project.
Thank you!