- 1. Visualizing non-functional requirements
-
- Neil Ernst and Yijun Yu and John Mylopoulos
2. Overview
- Many visualization techniques
- Most focus on functional artifacts
-
- code, design, architecture, requirements
- Move visualization towards problem-solving rather than problem
representation
- Use non-functional system qualities usability, security, trust,
performance to represent goals users have in analyzing a
system
3. Context
- Inspiration: Performance visualization
-
- Use colour to show performance impact of cache
optimizations
- Expand on existing softgoal/NFR support in the i* modeling
tool, OpenOME
4. 5. Goal evaluation
- Assign criteria to certain goals, and try to reason about
cascading effects
- Several algorithms for reasoning about a goal model
- We chose an algorithm for bottom-up reasoning
6. 7. NFR Evaluation
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- certainty how confident is the modeler that a soft-goal will be
achieved?
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- feasibility degree of deniability, likelihood of not being
accomplished inverse deniablility
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- trustability assigned value based on actor relationships (end
of chain trust future work)
-
- performance assigned by modeler by assessing task goals,
relative to other goals
8. Visualizing NFRs
- 2 approaches: operationalize or orthogonalize
- Use visual variables (Bertin83):
9. Bertin's visual variables
from:http://www.math.yorku.ca/SCS/Gallery/images/bertin-ve.jpg 10.
11. 12. Evaluation
- No completed user testing
- Used cognitive dimensions [Green89] as heuristic
walkthrough
- Fairly strong in viscosity, secondary notations, hard mental
operations can use the diagram for scenario evaluation, weighing of
options
- Challenges are in scalability and abstraction
- Limited visual variables (look at size, position, shape,
texture/pattern)
13. Future work
- Add an algebra for composing and abstracting relationships
- Difficult to quantify some NFRs accurately, e.g. usability
- Empirical usability testing
- Currently working on using Eclipse technologies e.g. GEF/GMF to
visualize conceptual models
14. References
- [Green89] - Green, T.R.G.Cognitive dimensions of notations . In
People and Computers V, Sutcliffe, A. & Macaulay, L. (ed.),
Cambridge University Press, 1989, pp. 443-460.
- [Bertin83] Bertin, J.Semiology of graphics: diagrams, networks,
maps . University of Wisconsin Press, Madison: 1983.
15.