Analysis of the criteria adopted in industry to extract microservices

A microservice architecture is expected to provide a better modularization and management of small and autonomous services. Other expected benefits include increased availability and time to market. There is a growing interest of both industry and academia on streamlining the migration of existing systems to a microservice architecture. However, the success of this migration is largely dependent on the use of appropriate criteria for extracting microservices from a code base. Recent studies indicate the selection and decomposition of microservices represent the main challenge along the migration. Academic techniques tend to support the extraction of microservices with either one or two conventional criteria, namely coupling and cohesion. There is limited knowledge on the criteria actually considered as useful by practitioners. Thus, we have performed an exploratory online survey with 15 specialists experienced on migrating systems to a microservices architecture. In particular, we question the relative usefulness of seven possible criteria for supporting decision-making along microservice extraction. The participants were also questioned about tools they have used, their limitations, and whether the decisions on extracted microservices were considered unsuccessful. Overall, the survey results suggest academic techniques do not totally satisfy the needs of practitioners. Practitioners often need to consider simultaneously at least four dominant criteria as well as their trade-offs to support their decisions. Most practitioners consider existing tooling support insufficient or even irrelevant to support their microservice extraction decisions.