Blockchain Interoperability Patterns

Design patterns are best practices for known problems in a specific context, and many have been proposed in different domains (e.g. object-oriented programming and microservices). However, blockchain interoperability is a recent area of work, and little effort has been made to identify patterns that help software architects design their interoperability solutions. Without this knowledge, solving blockchain interoperability becomes complex and costly. This work aimed to identify design patterns in existing interoperability solutions. Through observing 35 blockchain interoperability solutions, we identified four new patterns and two already identified patterns in the literature. A detailed specification was built using the Alexandrian template and was evaluated with five semi-structured interviews with blockchain experts regarding its clarity, completeness, and utility. The results showed that all interviewees identified the patterns. However, patterns' specifications have different degrees of clarity, completeness, and utility. Finally, all interviewees thought that the proposed patterns might be helpful to software architects in their first blockchain interoperability project.