DDD — Notes from the big blue book. Part 2

Today’s notes cover chapter 3 and 4.

Chapter 3

• Model must work well as analysis and design
• based on domain
• but is also solid code that plays well with technology choices
• If the model doesn’t fit the practical implementations — find a new one
• Start with the domain — then make the code fit
• Simple application features can be exposed as important domain features
• Example of the scripts for the net rules
• Reveal the “bones” of the software so users can make the most benefit of the technology
• So just have one model
• Example was IE favourites
• *** Discuss this point ***
• Domain modellers have to be coders. This is important for quick feedback and keeping the model consistent with the domain. The book talks about it being impossible to work otherwise

Chapter 4

• Responsibility driven design is used in the book as part of domain modelling
• Use layered architecture to separate concerns
• ** Important step is to isolate the domain model **
• Don’t allow other layers, eg ui, to influence the design of the domain
• Put logic like email sending in the infrastructure layer and expose interfaces to the other layers
• Important to minimise framework dependencies from the domain model