The role of modularity in free/open source software development

Software design and development in Free/Open Source projects are analyzed through the lens of the theory of modularity applied to complex systems. We review a series of software projects and we claim that both the architecture of the artifacts and the organization of the projects benefited from the paradigm of modularity, in an original and effective manner. In particular, our study shows that three main routines, or shortcuts, emerged and were effectively applied. First, some successful projects inherited previously existing modular architecture, rather than designing new modular systems from scratch. Second, popular modular systems, like GNU/Linux kernel, evolved from an initial integrated structure through a process of evolutionary adaptation. Third, development of modular software took advantage from the violation of one fundamental rule of modularity, namely, information hiding. Implications and extensions of Free/Open Source projects’ experience are discussed in the conclusions.