Exploring the Evolution of Software Quality with Animated Visualization

1. Exploring the Evolution of Software Quality with Animated Visualization Guillaume Langelier, Houari Sahraoui, Pierre Poulin Université de Montréal

2. Introduction • Visualization of software quality and its evolution • Animated transitions between versions • Use of graphical coherence

3. Nightmare of a project Manager • An old system has grown and has become very complex over the years. Everyone is afraid to be assigned to the project. • Abandon and start over! • A project manager has to figure out what happened, why the program has become poorly maintainable and possibly find a version from which to restart in the history database. • No! Abandon and start over! • How is it possible for the manager to assess millions of lines of code possibly modified in many versions? • Abandon and start over?!?

4. Plan • Problem Statement and Previous Work • Data • Single Version Representation • Software and Graphical Coherence • Multiple Version Representation • Switching between Views • Conclusion

5. Problem Statement • Quality • Quality is known as a major concern in software development • Evolution is required to understand the steps leading to a certain problem • Large amounts of data need to be analyzed • Existing approaches for analysis • Fully manual approaches are impractical • Too much information • Fully automatic approaches are imprecise • Quality aspects are not systematically defined • Solution : Visualization a semi-automatic approach

6. Previous Work(Visualization of software evolution) • Single Frame with data aggregation • Less information displayed • Multiple Frames shown side by side • Less entities displayed • Animation • Graph-based • Bayer (CVS) • Collberg (code)

7. Approach Overview • Evolution analysis using visualization • Determine data to be extracted • Pertinent to quality analysis • Data easy to visualize • Visualize it for analysis • Must take perception issues into account • Must avoid the problem generated by the great amount of data spawning multiple versions

8. Data • Metrics • Measures on software aspects • Structural metrics • Coupling • Complexity/Size • Cohesion • Other • Version control metrics • Author • Change magnitude • Number of versions since last change • Architecture • Package hierarchy

9. Visualization Approach • Single Version Visualization • Multiple Version Visualization

10. Single Version Visualization • Classes  3D Boxes • Color (scale from blue to red) • Height • Twist (rotation around the Up axis) • Layout • Treemap layout • Color separators

11. Single Version Representation (Example)

12. Multiple Version Visualization • Software coherence • A version is constructed from a previous one • Strong similarities between adjacent versions • Modifications are often small and targeted • Graphical coherence • High similarities between two images • Similar to a movie • Small cognitive effort • Only assess the differences • Do not have to reconstruct our virtual representation

13. Graphical Coherence(no spatial coherence) From Rensink RA, O'Regan JK, and Clark JJ (1997). “To See or Not to See: The Need for Attention to Perceive Changes in Scenes”. Psychological Science, 8.

14. Graphical Coherence(spatial and temporal coherences) From Rensink RA, O'Regan JK, and Clark JJ (1997). “To See or Not to See: The Need for Attention to Perceive Changes in Scenes”. Psychological Science, 8.

15. Multiple Version Representation • Class animation • Characteristics are animated individually with linear interpolation • Movement and characteristics animation in two distinct phases

16. Layout Animation • Integrate spatial coherence in the visualization of the evolution • Displaying single version representations one after the other is not satisfactory • Class movements cross each other • Lost the unique virtual representation • Two algorithms • Static position layout (class tracking) • Relative position layout (space reduction)

17. Layout Animation • Static Position Animation • Each class remains at the same position for all versions • Positions are computed for a merged tree containing all classes existing in at least one version • Classes are only displayed when they exist in the current version

18. Static Layout Animation

19. Layout Animation • Relative Position Animation • Classes keep a relative position to each other • Computed from the static position animation • Classes are moved left or down until they reach their nearest neighbor

20. Relative Position Animation

21. Switching between Views • Require to access CVS metrics during evolution • Limited number of graphical attributes • Creation of a second mapping of graphical attributes • Same entities at same positions(spatial coherence) • Additional information is fetched instantly on demand without introducing a cognitive gap

22. Switching between Views

23. Applications • Exploration • Gather information from a new system with free exploration • Exploration of Azureus(Responsibility transfer, class renaming, etc …) • Verification of automatic analysis • Calibrate automatic approach • Tune rules and their threshold • Oracles for machine-learning algorithms • Study of evolution patterns • Study different types of evolution and how they affect quality aspects • Blob: Instant grown, gradual grown, up and down pattern

24. Conclusion • We presented an approach that uses… • Visualization and metrics to represent software • Animation to represent transition between versions • Layout and animation • Static Layout • Relative Position Layout • Exploit multiple views • Future work • User study • Semantic zoom • More views (Bug view, Management View, Performance View)