An Integrated Metric for Modularity in a Microservice System

Microservices architectures offer significant advantages, including independent deployment, scalability, and improved system flexibility. Nonetheless, as the number of services increases, systems often experience diminished modularity, resulting in architectural degradation. We propose a comprehensive modularity assessment framework that systematically integrates three dimensions of modularity for a microservice system: inter-service coupling, intra-service cohesion, and data dependency. An integrated modularity score that aggregates these individual metrics presents overall architectural modularity. We also evaluate the propose framework by experimenting with seven JavaScript-based microservice systems. The evaluation result demonstrates the framework's ability to identify modularity-related issues and variations across services. The findings provide actionable insights to inform architectural decision-making and promote more maintainable, scalable, and modular microservice systems.