Software Systems as Cities

Software understanding takes up a large share of the total cost of a software system. The high costs attributed to software understanding activities are caused by the size and complexity of software systems, by the continuous evolution that these systems are subject to, and by the lack of physical presence which makes software intangible. Reverse engineering helps practitioners deal with the intrinsic complexity of software, by providing a broad range of patterns and techniques. One of these techniques is software visualization, which makes software more tangible, by providing visible representations of software systems. Interpreting a visualization is by no means trivial and requires knowledge about the visual language of the visualization. One means to ease the learning of a new visualization's language are metaphors, which allow the interpretation of new data representations by analogy. Possibly one of the most popular metaphors for software visualization is the city metaphor, which has been explored in the past by a number of researchers. However, in spite of the efforts, the value of this metaphor for reverse engineering has never been taken beyond anecdotical evidence. In this dissertation, we demonstrate the value of the city metaphor for reverse engineering along two directions. On the one hand, we show that the metaphor is versatile enough to allow the representation of different facets of software. On the other hand, we show that the city metaphor enables the creation of software visualizations which efficiently and effectively support reverse engineering activities.