GASE: visualizing software evolution-in-the-large

Large and long lived software systems, sometimes called legacy systems, must evolve if they are to remain useful. Too often, it is difficult to control or to understand this evolution. The paper presents an approach to visualizing software structural change. A visualization tool, called GASE (Graphical Analyzer for Software Evolution), has been used to elucidate the architectural changes in a sequence of eleven revisions of an eighty thousand line industrial software system.