Extraction of Configurable and Reusable Microservices from Legacy Systems: An Exploratory Study

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. Migration to a microservice architecture is increasingly becoming the focus of academic research. However, there is little knowledge on how microservices are extracted from legacy systems in practice. Among these limitations, there is a lack of understanding if variability is considered useful along the microservice extraction from a configurable system. In order to address this gap, we performed an exploratory study composed of two phases. Firstly, we conducted an online survey with 26 specialists that contributed to the migration of existing systems to a microservice architecture. Secondly, we performed individual interviews with seven survey participants. A subset of the participants (13 out of 26) dealt with systems with variability during the extraction, which stated that variability is a key criterion for structuring the microservices. Moreover, variability in the legacy system is usually implemented with simple mechanisms. Finally, initial evidence points out that microservices extraction can increase software customization.