Polyptychon: A Hierarchically-Constrained Classified Dependencies Visualization

Architects and developers are often tasked with evaluating or maintaining unfamiliar software systems. Reverse engineering tools help extract relationships between the system parts as they exist instead of as documented. Though node-link diagrams have a straightforward correspondence with the graph-represent able data generated, the scale and complexity of real-world data sets prevent efficient comprehension. This paper presents Polyptychon, an interactive node-link visualization designed for incremental exploration of dependency information. Given a hierarchical information space of software artifacts, Polyptychon constrains the visible dependencies to be related to the child nodes of a specified artifact node, called a view root. It then classifies these siblings as levelized, tangled and independent. It also includes context nodes, which are a filtered set of nodes elsewhere in the hierarchy that are related to the siblings. The context nodes are further grouped based on a project-specific partition function. The hierarchical constraints and partition function provide means to control the number of nodes displayed, while the dependency classification allows users to form a qualitative impression of the dependency structure. We demonstrate with examples from the Netty open source project. We conclude with areas of future work, in particular, as a basis of evolutionary dependency analysis.