title: Software systems as complex networks: structure, function, and evolvability of software collaboration graphs.
abstract: Software systems emerge from mere keystrokes to form intricate functional networks connecting many collaborating modules, objects, classes, methods, and subroutines. Building on recent advances in the study of complex networks, I have examined software collaboration graphs contained within several open-source software systems, and have found them to reveal scale-free, small-world networks similar to those identified in other technological, sociological, and biological systems. I present several measures of these network topologies, and discuss their relationship to software engineering practices. I also present a simple model of software system evolution based on refactoring processes which captures some of the salient features of the observed systems. Some implications of object-oriented design for questions about network robustness, evolvability, degeneracy, and organization are discussed in the wake of these findings.
authors.affiliation: Cornell Theory Center, Rhodes Hall, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Myers