Community-Driven Variability: Characterizing a new Software Variability Paradigm

Both software engineering researchers and practitioners have increasingly shifted their focus from single software systems to software families, reflecting the need for software industrialization through systematic reuse of implementation artifacts. Interestingly, several vibrant ecosystems produce software families in a radically different way than classical variability-intensive systems, notably software product lines (SPLs). The Bitcoin community, for instance, evolves its ecosystem through crowdsourced improvement proposals being continuously shaped and autonomously implemented by independent actors. While this novel paradigm of Community-Driven Variability (CDV) has proven effective for driving flourishing technologies like Bitcoin and others, it also comes with unique challenges calling for novel solutions. In this paper, we define the key characteristics of ecosystems exposing CDV and derive a taxonomy that hierarchically decomposes each characteristic into constituting sub-characteristics. Building on the taxonomy, we conduct a systematic analysis of 14 software ecosystems to evaluate the presence and nature of CDV. We highlight the novel problems they face, such as the lack of ecosystem overview, difficulties in impact assessment, misalignment between proposals and implementations, and interoperability breakdowns – challenges that transcend classical variability management. Based on the problem analysis, we outline our research vision to tackle these challenges, including a sketch of concrete starting points for technical solutions. While classical SPLs and CDV ecosystems differ drastically, we believe that feature-oriented modeling and analysis offers promising concepts for addressing CDV challenges without enforcing product-line processes. Conversely, the unique demands of CDV can inspire advances in variability research with impact beyond its original domains.