Towards a security-optimized approach for the microservice-oriented decomposition

Microservice architecture (MSA) is a mainstream architectural style due to its high maintainability and scalability. In practice, an appropriate microservice-oriented decomposition is the foundation to make a system enjoy the benefits of MSA. In terms of decomposing monolithic systems into microservices, researchers have been exploring many optimization objectives, of which modularity is a predominantly focused quality attribute. Security is also a critical quality attribute, that measures the extent to which a system protects data from malicious access or use by attackers. Considering security in microservices-oriented decomposition can help avoid the risk of leaking critical data and other unexpected software security issues. However, few researchers consider the security objective during microservice-oriented decomposition, because the measurement of security and the trade-off with other objectives are challenging in reality. To bridge this research gap, we propose a security-optimized approach for microservice-oriented decomposition (So4MoD). In this approach, we adapt five metrics from previous studies for the measurement of the data security of candidate microservices. A multi-objective optimization algorithm based on NSGA-II is designed to search for microservices with optimized security and modularity. To validate the effectiveness of the proposed So4MoD, we perform several experiments on eight open-source projects and compare the decomposition results to other three state-of-the-art approaches, that is, FoSCI, CO-GCN, and MSExtractor. The experiment results show that our approach can achieve at least an 11.5% improvement in terms of security metrics. Moreover, the decomposition results of So4MoD outperform other approaches in four modularity metrics, demonstrating that So4MoD can optimize data security while pursuing a well-modularized MSA.