A Metrics Framework for Evaluating Microservices Architecture Designs

Microservices are becoming a more popular software architecture among companies and developers. Therefore, there is a need to develop methods for quantifying the process of measuring the quality of microservices design. This paper has created a novel set of metrics for microservices architecture applications. The proposed metrics are the Service Granularity Metric “SGM”, the Lack of Cohesion Metric “LCOM”, and the Number of Operations “NOO”. The proposed metrics measure the granularity, cohesion, and complexity of individual microservices through analyzing the application programming interface “API”. Using these metrics, it is possible to evaluate the overall quality of the design of microservices applications. The proposed metrics were measured on 5 applications with different sizes and business cases. This research found that the value for the SGM metric needs to be between 0.2 and 0.6. Besides, the value of LCOM metric for a microservice needs to be between 0 and 0.8 with less than ten operations per microservice. These findings can be applied in the decomposition process of monolithic applications as well.