Leveraging Metamodels and DCI to Build Modular Monoliths (Dan Haywood)

Metamodels provide a solution to the horizontal layering problem. In the same way that an ORM such as Hibernate uses a metamodel to separate the domain model from its persistence model, so too can a metamodel be used to - among other things - separate out the application and presentation layers. Splitting vertical subdomains is a different challenge again, but DCI - an evolution of the well-known MVC pattern - is an architectural style that helps achieve that goal. Distinguishing between data (what the system is), interaction (what the system does), and context (what the user is trying to do), it sits somewhere between aspect-oriented and object-oriented approaches. Its the aspect-oriented nature that allows functionality to be partitioned into vertical submodules but nevertheless be presented in a coherent fashion to the end-user. So much for the theory. In this live coding session we'll look at a framework that marries both of these techniques, resulting in applications with clean separation both vertically and horizontally.