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Re: Layers, hexagons, features and components

Hi Simon, thanks for the link. I'd like to add few comments here:

- "everything on the inside is expressed in the ubiquitous language, so you'll see terms like "Repository" rather than "Data Access Object".": in fact on the inside (i.e. Domain code kingdom) you won't find any reference to "Repository" types because you will name them instead with the (ubiquitous) language of your business (e.g. ProductCatalog, Lexicon, etc.)

- "the interface (port) and implementation class (adapter) are both public.". There has been much debate on this subject but after few checks with Alistair and other happy few, the "port" describe something you don't code (i.e. a middleware API, a database driver, a springboot REST exposition, etc.) whereas the "Adapter" is what we code in order to bridge the 2 separated worlds: the infrastructure code where the adapter belongs and the Domain code the Adapter interacts with.

- "especially if all types are marked as public.": Everything marked as public? Hell no! That's an orthogonal topic but you shouldn't do that of course. I'll have to dig more about how to make it in java but in .NET I used to create 2 projects/assemblies(packages?): one for the "MyAppOrServiceTopic.Domain" and the other for "MyAppOrServiceTopic.Infra". Since the "Infra" assembly is referencing the "Domain" one, there is no way for the Domain assembly code to reference any Infrastructure Implementation (you can't have such cross project reference in .NET). BTW, within the "Infra" assembly I only set 'public' the various (Repository) implementation types that are needed by the app bootstrapper (i.e. composition root which is part of the Infrastructure kingdom) or by the Domain code (via the magic of the Dependency Inversion Principle - DIP). All the other infrastructure types are set 'internal' (or 'public' if we become lazy) for my tests to work with.

Re: Layers, hexagons, features and components

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