Miljenko Švarcmajer, Mirko Kohler, Zdravko Krpić, Ivica Lukić
Modern data-driven distributed systems increasingly rely on blockchain technologies to ensure trust, transparency, and decentralized coordination. However, the rapid proliferation of consensus mechanisms has created a complex design space, making the selection of an appropriate protocol a non-trivial architectural and decision-making challenge. Different consensus mechanisms rely on distinct security resources, validator admission models, and agreement architectures, leading to diverse trade-offs between scalability, decentralization, performance, and governance. Existing studies primarily focus on classification or performance comparison of consensus mechanisms, while the problem of systematic, requirement-driven selection remains insufficiently addressed. In particular, there is a lack of structured approaches that integrate multiple system requirements into a unified decision framework suitable for real-world environments. To address this gap, this paper proposes a consensus-driven, layered framework for blockchain consensus mechanism selection, formulated as a multi-criteria decision problem. The framework organizes the consensus design space across key architectural dimensions and analyzes 32 consensus mechanisms, enabling systematic comparison and supporting data-driven decision-making. The approach is further demonstrated through five representative use-case scenarios, showing its applicability in optimizing distributed system design.