Actor-driven Decomposition of Microservices through Multi-level Scalability Assessment

The microservices architectural style has gained widespread acceptance. However, designing applications according to this style is still challenging. Common difficulties concern finding clear boundaries that guide decomposition while ensuring performance and scalability. With the aim of providing software architects and engineers with a systematic methodology, we introduce a novel actor-driven decomposition strategy to complement the domain-driven design and overcome some of its limitations by reaching a finer modulariza- tion yet enforcing performance and scalability improvements. The methodology uses a multi-level scalability assessment framework that supports decision-making over iterative steps. At each iteration, architecture alternatives are quantitatively evaluated at multiple granularity levels. The assessment helps architects to understand the extent to which architecture alternatives increase or decrease performance and scalability. We applied the methodology to drive further decomposition of the core microservices of a real data-intensive smart mobility application and an existing open-source benchmark in the e-commerce domain. The results of an in-depth evaluation show that the approach can effectively support engineers in (i) decomposing mono- liths or coarse-grained microservices into more scalable microservices and (ii) comparing among alternative architectures to guide decision-making for their deployment in modern infrastructures that orchestrate light- weight virtualized execution units.