Stepwise migration of a monolith to a microservice architecture: Performance and migration effort evaluation

Due to scalability requirements and the split of large software development projects into small agile teams, there is a current trend toward the migration of monolith systems to the microservice architecture. However, the split of the monolith into microservices, its encapsulation through well-defined interfaces, and the introduction of inter-microservice communication add a cost in terms of performance. In this paper, we describe a case study of the migration of a monolith to a microservice architecture, where a modular monolith architecture is used as an intermediate step. The impact on migration effort and performance is measured for both steps. Current state-of-the-art analyses the migration of monolith systems to a microservice architecture, but we observed that migration effort and performance issues are already significant in the migration to a modular monolith. Therefore, a clear distinction is established for each of the steps, which may inform software architects on the planning of the migration of monolith systems. In particular, we consider the trade-offs of doing all the migration process or just migrating to a modular monolith.