Software landscape and application visualization for system comprehension with ExplorViz

- Hierarchical and multi-layer visualization of large software landscapes with ExplorViz, generated from monitoring traces.
- Reusable design and execution of a controlled experiment comparing a flat landscape visualization to our hierarchical landscape visualization in system comprehension tasks.
- Controlled experiments for comparing ExplorViz with the Extravis trace visualization approach, for employing physical 3D-printed ExplorViz models, and for exploring 3D ExplorViz models in virtual reality.

Context: The number of software applications deployed in organizations is constantly increasing. Those applications - often several hundreds - form large software landscapes.Objective: The comprehension of such landscapes and their applications is often impeded by, for instance, architectural erosion, personnel turnover, or changing requirements. Therefore, an efficient and effective way to comprehend such software landscapes is required.Method: In our ExplorViz visualization, we introduce hierarchical abstractions aiming at solving system comprehension tasks fast and accurately for large software landscapes. Besides hierarchical visualization on the landscape level, ExplorViz provides multi-level visualization from the landscape to the level of individual applications. The 3D application-level visualization is empirically evaluated with a comparison to the Extravis approach, with physical models and in virtual reality. To evaluate ExplorViz, we conducted four controlled experiments. We provide packages containing all our experimental data to facilitate the verifiability, reproducibility, and further extensibility of our results.Results: We observed a statistical significant increase in task correctness of the hierarchical visualization compared to the flat visualization. The time spent did not show any significant differences. For the comparison with Extravis, we observed that solving program comprehension tasks using ExplorViz leads to a significant increase in correctness and in less or similar time spent. The physical models improved the team-based program comprehension process for specific tasks by initiating gesture-based interaction, but not for all tasks. The participants of our virtual reality experiment with ExplorViz rated the realized gestures for translation, rotation, and selection as highly usable. However, our zooming gesture was less favored.Conclusion: The results backup our claim that our hierarchical and multi-level approach enhances the current state of the art in landscape and application visualization for better software system comprehension, including new forms of interaction with physical models and virtual reality.

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