From ADR to BDR: Reasoning Patterns for Creating Blockchain Decision Records

Building software that uses blockchain technology is a challenging task as it increases the complexity and cost of the system. As decentralized technologies have a profound impact on the system architecture, the decision to use blockchain technology should be well-founded and justified by comprehensible reasons. Existing approaches in the area of blockchain-oriented software engineering focus on the implementation but lack support for the early requirements analysis and design phases. This paper introduces a new type of reasoning patterns which are derived from successful blockchain projects. The result is a blockchain pattern map which models the relationship between design patterns and reasoning patterns in a graph structure. Whereas design patterns explain how a specific component can be implemented on a technical level, the reasoning patterns also explain why for a given aspect blockchain technology should be used. Furthermore, we present a process to make this knowledge applicable. It guides a software engineer through the identification of potential areas for a given use case where blockchain technology is useful and gives comprehensible reasons for making that decision. By separating design patterns and reasoning patterns, the approach can be used by practitioners, even without deep blockchain knowledge.