Bootstrapping the Framework hexagon
When building a system using hexagonal architecture, you don't need to decide up front if the system API will be exposed using REST or gRPC, nor if the system's primary data source will be a MySQL database or MongoDB. Instead, what you need to do is start modeling your problem domain in the Domain hexagon, then designing and implementing use cases in the Application hexagon. Then, only after creating the previous two hexagons, you'll need to start thinking about which technologies will enable the hexagonal system's functionalities.
The hexagonal approach centered on Domain Driven Design allows us to postpone the decisions regarding the underlying technologies internal or external to the hexagonal system. Another prerogative of the hexagonal approach is the pluggable nature of the adapters. If you want to expose some system feature to be accessible through REST, you create and plug a REST input adapter into an input port. Later...
