Toward automatic decomposition of monolithic software into microservices

The microservices paradigm gains more and more traction, and many companies choose to adopt it for new developments as well as to transform existing monolithic software to be microservices-based instead. However, the latter approach bears many difficulties that involve much manual work, specifically in the early stages of such a decomposition process. Determining the boundaries between the services, where one service ends, and the next one begins, is a notoriously difficult task for which a lot of literature exists that however mainly helps with providing a framework to determine said boundaries manually, with Domain-driven design by Eric Evans laying the foundation for this entire domain of research. This thesis devises a methodology that automatically generates microservice candidate recommendations for any given piece of monolithic software. To do this, four dimensions of coupling are calculated out of the input software that each construct a weighted graph with the edges resembling coupling between the units of the software. Next, the four graphs are merged into one before being clustered by specifically surveyed and assessed state-of-the-art graph clustering algorithms — the resulting clusters then resemble the microservice candidate recommendations. Additionally, a large set of numeric metrics was formulated to evaluate the output of the methodology. Finally, the devised methodology was fully implemented, with an additional graphical user interface for ease of use, to work with input Java software while being easily extensible to be able to support other platforms in the future