Structural Coupling for Microservices
This work addresses the problem of quantifying service coupling for practitioners in cloud-native development, though it is incremental as it extends existing structural coupling concepts.
The paper tackled the lack of validated metrics for measuring coupling between microservices in cloud-native applications by proposing ways to compute and visualize structural coupling, validated through a case study with 17 open-source projects and an automatic measurement approach.
Cloud-native Applications are 'distributed, elastic and horizontal-scalable systems composed of (micro)services which isolate states in a minimum of stateful components'. Hence, an important property is to ensure a low coupling and a high cohesion among the (micro)services composing the cloud-native application. Loosely coupled and highly cohesive services allow development teams to work in parallel, reducing the communication overhead between teams. However, despite both practitioners and researchers agree on the importance of this general property, there are no validated metrics to effectively measure or test the actual coupling level between services. In this work, we propose ways to compute and visualize the coupling between microservices, by extending and adapting the concepts behind the computation of the traditional structural coupling. We validate these measures with a case study involving 17 open-source projects and we provide an automatic approach to measure them. The results of this study highlight how these metrics provide to practitioners a quantitative and visual view of services compositions, which can be useful to conceive advanced systems to monitor the evolution of the service.