Does Domain-Driven Design Lead to Finding the Optimal Modularity of a Microservice?

Information systems are moving into the cloud. The new requirements enforced by cloud standards are high availability, high scalability, and a reduced mean time to recovery. Due to these new requirements, information system architecture styles are also evolving. Microservice architecture is becoming the de facto standard for developing highly modular cloud information systems. Since microservices were introduced, there has been an ongoing debate concerning how to choose the granularity of a microservice. In this study, the optimal point of granularity for microservices is examined based on coupling and cohesion values. The present study is based on two design examples generated in previous studies that applied domain-driven design in proposing microservices. Both examples are modified to generate more and less granular microservices. The coupling and cohesion values of the original examples are compared to those of the more and less granular microservices. We observe that domain-driven design has delivered a good end result for finding modular microservices.