In the previous chapter, we discussed the benefits and downsides of a microservices-based approach. We named the main architectural properties of microservices such as autonomy, isolation, and data ownership. We also noted that, compared to the traditional monolithic approach, microservices reduce the complexity of a single service but the complexity of the system as a whole does not disappear. In a sense, it just moves from the internals of a single microservice into the space between them. We looked at the implementation of the shop as a RESTful microservice, and we admitted that we would avoid this additional complexity by focusing on a single service.
As we worked through the Akka-based solution, we also chose the proper database to store events as well as defining and applying migrations to have a proper database schema. The choice of the configuration mechanism...