Architect: A Framework for the Migration to Microservices

The migration from a monolithic to a microservice architecture is a recurring step in many software projects. With the increasing distributed nature of the transformed system, new challenges for data consistency and deployment arise, which can be counteracted by the integration of microservices patterns. However, the use of such patterns is complex and time-consuming. In this paper, we describe a case study of a migration process of the learning management system Artemis which consists of two phases. The first phase shows the transformation from a monolithic architecture to a microservice architecture with a shared database. It sets as a goal the identification of microservice boundaries, the decomposition of the monolith application into multiple distributed entities, as well as their orchestration in a cloud-ready environment. The second phase migrates the shared database into multiple databases based on the database-per-microservice pattern. While analyzing the current Artemis architecture, we describe a gradual refactoring of an existing application to decompose Artemis into multiple subsystems. We developed Architect, a framework which is based on a domain-specific language for building dependable distributed systems as a template to ensure the data consistency of the distributed transactions using the Saga pattern. We decomposed Artemis into 3 microservices and provided the migration concept from shared-database to database-per-microservice using Architect. The framework helped to reduce the complexity of using the Saga pattern. It introduced the eventual consistency in a distributed database system and decreased the coupling of the data storage. The migration to a microservice architecture solves many problems of a monolith application, but introduces new challenges and increases the complexity of the overall system. Architect focuses on greenfield project, but currently does not provide a software evolution approach. We will add support for reengineering projects, which can facilitate the migration process of existing system.