1. Software Visualization

2. Visualization “A picture is worth 1000 words”
Effective visualization can help with the understanding of complex structures
The key word is “effective”
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3. Compare this with… useproc ds.pl9 artificial.pl9
useproc ds.pl9 dsdbg.pl9
useproc ds.pl9 dselim.pl9
useproc ds.pl9 dsinit.pl9
useproc ds.pl9 dslivlst.pl9
useproc ds.pl9 dslvbb.pl9
useproc ds.pl9 dslvrg.pl9
useproc ds.pl9 dsmemuse.pl9
useproc ds.pl9 errorbe.pl9
useproc ds.pl9 ilstats.pl9
useproc dsdbg.pl9 artificial.pl9
useproc dsdbg.pl9 both.pl9
useproc dsdbg.pl9 getval.pl9
useproc dselim.pl9 dsdbg.pl9
useproc dselim.pl9 dslivlst.pl9
useproc dselim.pl9 dsmdlv.pl9
useproc dselim.pl9 dsmrgs.pl9
useproc dselim.pl9 gen_bag.pl9
useproc dselim.pl9 pl_del.pl9
useproc dselim.pl9 storame.pl9
useproc dsinit.pl9 alias.pl9
useproc dsinit.pl9 artificial.pl9
useproc dsinit.pl9 blevel1.pl9
useproc dsinit.pl9 both.pl9
useproc dsinit.pl9 choprnd.pl9
useproc dsinit.pl9 dslivlst.pl9
useproc dsinit.pl9 dsmemuse.pl9
useproc dsinit.pl9 getval.pl9
useproc dsinit.pl9 ilstats.pl9
useproc dslivlst.pl9 artificial.pl9
useproc dslivlst.pl9 dslivlst.pl9
useproc dslivlst.pl9 dsmemuse.pl9
useproc dslvbb.pl9 dslivlst.pl9
useproc dslvbb.pl9 dsmdlv.pl9
useproc dslvrg.pl9 dslivlst.pl9
useproc dslvrg.pl9 dslvrg.pl9
useproc dslvrg.pl9 dsmdlv.pl9
useproc dslvrg.pl9 dsmrgs.pl9
useproc dsmdlv.pl9 dslivlst.pl9
useproc dsmdlv.pl9 dsmdlv.pl9
useproc dsmrgs.pl9 dslivlst.pl9
useproc dsmrgs.pl9 dsmdlv.pl9
useproc optimiz.pl9 ds.pl9
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5. Key questions What views are useful? What technique to use?
Low-level or high-level
Kind of information displayed (procedure calls, data flow, control flow, inheritance)
What technique to use?
Automatic graph layout
Animation
What part of the information should be elided?
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6. Low-level visualizations
Execution of algorithms can be visualized to help with their understanding
Classic example: “Sorting out Sorting”
Many tools have been developed to do this automatically
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7. Parallel Quicksort visualization
The left view shows the values being sorted (color indicates thread) and the right view shows a history of the swaps made in the program.
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8. Automatic graph layout
Given a graph, what is its most understandable layout?
Understandability usually refers to number of edge crossings
A tough problem in the general case
Minimizing edge crossings for a bipartite graph with one side fixed is NP-hard
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9. Heuristics - Sugiyama
In software systems, one often deals with layered graphs
Sugiyama developed a widely used algorithm for layout of layered graphs
Main idea: Minimize edge crossings by having edges be as vertical as possible Abscissa of each vertex is the average of the abscissas of its neighbours
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10. Sugiyama example
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11. Heuristics – Spring Layout
Attaches forces between the nodes of a graph
Connected nodes are attracted to each other, otherwise they are pushed apart
Converges to a stable position
Of dubious value for systems with many cycles (as most software systems are)
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12. Spring Layout example
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13. Graphviz Set of graph drawing tools from AT&T
Supports both Sugiyama and Spring layout
Has been used in a number of different settings
Receives textual input and transforms it into graphs
Bunch can produce output that Graphviz can visualize
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14. Data structures
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15. Automata
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16. Program profile
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17. Module dependencies
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18. Rigi
Interactive, visual tool designed to help understand and re-document software
Includes parsers for C, C++, and COBOL
Incorporates selection, filtering, and editing operations
Uses simple file format to represent graphs (RSF)
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19. SHriMP Views Simple Hierarchical Multi-Perspective
Originally developed for program understanding
Can be used for other knowledge bases as well
Usual problem: How does it scale up?
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20. 3D Visualizations
A number of papers present attempts to visualize software structures in 3D
While interesting, it is doubtful that these approaches can be useful (see aside on the course webpage)
Some examples….
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21. Metaballs
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22. Cone trees
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23. World cities
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