Evolution of a Modular Software Network

TL;DR

This study examines the evolution of modularity in the Debian GNU/Linux system, revealing that increased modularity enhances local package functionality despite rising incompatibilities, with implications for understanding biological network evolution.

Contribution

It provides a novel analysis of software network evolution using modularity concepts, highlighting the balance between modularity benefits and incompatibility costs.

Findings

Higher modularity correlates with more packages functioning properly locally.

Incompatibilities within modules increase over time but do not impair overall system functionality.

Modularity evolution in software parallels ecological network dynamics.

Abstract

"Evolution behaves like a tinkerer" (Francois Jacob, Science, 1977). Software systems provide a unique opportunity to understand biological processes using concepts from network theory. The Debian GNU/Linux operating system allows us to explore the evolution of a complex network in a novel way. The modular design detected during its growth is based on the reuse of existing code in order to minimize costs during programming. The increase of modularity experienced by the system over time has not counterbalanced the increase in incompatibilities between software packages within modules. This negative effect is far from being a failure of design. A random process of package installation shows that the higher the modularity the larger the fraction of packages working properly in a local computer. The decrease in the relative number of conflicts between packages from different modules avoids a failure in the functionality of one package spreading throughout the entire system. Some potential analogies with the evolutionary and ecological processes determining the structure of ecological networks of interacting species are discussed.