Monolith to Microservices: Refactoring Approaches compared: Transforming Applications to could-ready Software Architectures

While the recently emerged Microservice Architecture pattern is widely discussed in literature, it is difficult to find clear guidance on the process of refactoring legacy applications. Informal sources of information offer lots of advice, but scientific studies providing structured and validated approches are still rare. Architects and decision makers are in need to assess the benefit by balancing pros and cons of an architecture transformation upfront and in the next step, select an appropriate strategy and refactoring technique. One of the most discussed aspects in this context is finding the right service granularity to fully leverage the advantages of the microservice pattern. This book gives an insight into the topic by first comparing the Monolithic and Microservice Architecture patterns based on the ISO/IEC 25010 quality model. Secondly, the notion of architectural refactoring is discussed and followed by a comparison of 10 refactoring approaches recently proposed in academic literature. The concluding part identifies quality attributes and related metrics for assessing the quality of a decomposition based on cohesion and coupling metrics.