Summary
In this chapter, we started by looking into the motivations and benefits behind JPMS. We discovered that one of the problems JPMS helps to solve is that of JAR hell, where it's difficult to control the dependencies that an application should expose and use. JPMS addresses this problem by closing access to every public type in a module, requiring the developer to explicitly state which packages containing public types should be visible to other modules. Also, the developer should state the modules that a given module depends on in the module descriptor.
We discussed the DIP and recognized the use cases, input ports, input adapters, and output adapters as components that we can apply to the DIP. Then, we used JPMS features such as consumers, services, and providers to refactor the topology and inventory system to enable dependency inversion in conjunction with hexagonal architecture components.
By employing DIP, we created a more supple design, an important characteristic...
