Re-engineering legacy systems as microservices: An industrial survey of criteria to deal with modularity and variability of features

Abstract

Microservices is an emerging industrial technique to promote better modularization and management of small and autonomous services. Microservice architecture is widely used to overcome the limitations of monolithic legacy systems, such as limited maintainability and reusability. The re-engineering of monolithic legacy systems into microservice-based architectures has been receiving great attention from industry and academia lately. However, there is little knowledge on how professionals perform microservice extraction to conduct the re-engineering process. In particular, there is not much information of how legacy features should be modularized and customized as microservices, while managing variability, to fulfill customer needs. In order to address this gap, we performed a study composed of two phases. Firstly, we conduct an online survey with 26 specialists that contributed to the migration of legacy systems to a microservice architecture. Secondly, we conduct individual interviews with seven participants of the survey. The results reveal that criteria related to modularity such as coupling, cohesion, and reuse are considered useful during the microservice extraction. Half of the participants dealt with systems with variability during the extraction. Moreover, they stated that variability is a key criterion for structuring the microservices.