In this post I discuss the subtle relationship between bounded contexts and sub-domains within strategic Domain-Driven Design. The concepts often seem elusively similar, yet in reality are more like parallels. To understand the parallels, the association between a domain of discourse and the corresponding model shall be investigated. My understanding of the subject matter was honed at DDD Denver Lean Coffee Discussions organized by Paul Rayner.

In this post I dig deeper into validation of a Domain-Driven Design with F# and the functional paradigm. The implementation builds upon the design introduced earlier. The central theme is that of explicitness - the possibility of a failure is made explicit with type signatures. In turn, this calls for explicit handling of failure conditions paving the way for a design-by-contract style of programming and equational reasoning. Under the hood, the implementation draws on basic principles of category theory which provide for uniformity and composability. As a result, from the perspective of DDD, the confluence of declarative design, supple design, invariants and assertions is tremendously enhanced. The functional implementation of validation is to a great extent based on the wonderful work of Mauricio Scheffer.

Adoption of Domain-Driven Design follows a pattern akin to REST as expressed by the Richardson Maturity Model. Such a model, while not set in stone, can serve as a convenient anchor to gauge one’s place on the path to DDD nirvana. Ultimately, the maturity model illustrates a more detailed analysis of Domain-Driven Design adoption beyond the Two sides of DDD.

In this post I describe some of the subtleties involved in the formation of a ubiquitous language and domain modeling efforts in general. In particular, I fixate on the difficulties in making distinctions among concepts given a natural tendency to conflate terms and the implicit capacity to extract meaning from context.

This post explores Domain-Driven Design from the tactical and strategic perspectives with the goal of clearing confusion around these orthogonal axes. Motivation sourced from Outside In TDD versus DDD by Mark Seemann where the author examines this misunderstanding surrounding DDD.