Layout Merging with Relative Positioning

ABSTRACTThe advent of modeling in software engineering, like other engineering fields, has revolutionized the formalism and pace of software development. However, software applications are not built from scratch, instead, other existing software artifacts are reused and combined with new artifacts. This notion of software reuse has been in existence for decades. When structural models such as class diagrams are reused, the reusing and reused models often need to be merged and the result visualized to the modeler. However, layout mechanisms such as GraphViz, JGraphX, and other related layout tools do not retain the original layout and rather arbitrarily layout the merged models. Therefore, important information that corresponds to the mental map of a modeler and is conveyed by the specific layout is currently lost. This paper aims to establish a robust layout algorithm called rpGraph that retains the general layout of the reusing and reused models after merging. rpGraph uses the relative positioning of model elements to inform the positioning of merged model elements. Our findings are evaluated with 20 example model reuses from a library of reusable software model artifacts. A comparison of the merged layouts of rpGraph, GraphViz, and JGraphX shows that rpGraph performs better in terms of retaining the original layouts.