Finding The Sweet Spot

DDD, CQRS, and ORMs - Finding the sweet spot between these development techniques

Transcript

1. Community Partners
   

   View Slide

2. 12 August 2017 | Andrew Best
   

   View Slide

3. Domain Driven Design
   At it’s heart, DDD is about
   TAMING COMPLEXITY
   It allows us to reason about the software we are building,
   explicitly modelling our problem domain in unambiguous terms
   and supplying well-defined semantics for its concepts.
   August 17 2
   

   View Slide

4. Meet the > Our domain model facilitates the real-world process
   requirements from our problem domain – This is what it
   should be doing
   > Our applications’ demands on their persisted state extend
   beyond our domain model – Task-based UIs, Reporting,
   Exporting, etc.
   > Often the domain model becomes the single façade over our
   persistence layer – it is set to work servicing these additional
   demands as well
   > It then becomes MORE COMPLEX
   > It then becomes HARDER TO REASON ABOUT
   > And then you add an ORM
   August 17
   

   View Slide

5. “
   Object/relational mapping is
   the Vietnam of Computer
   Science
   Ted Neward
   http://blogs.tedneward.com/post/the-vietnam-of-computer-science/
   

   View Slide

6. The Codes, Part One:
   Death to the
   Repository!
   

   View Slide

7. CQRS >Event Sourcing
   >Eventual Consistency
   >Asynchronous Messaging
   >Separate Persistence
   Mechanisms
   August 17
   

   View Slide

8. CQRS >Using separate conceptual
   models to read and write
   information.
   >fin
   August 17
   

   View Slide

9. The Codes, Part Two:
   The Sweet Spot
   

   View Slide

10. CQRS >Read and write concerns truly
    separated
    >Can co-evolve without side
    effects
    >Minimal additional complexity
    >Use the best tool for the job
    August 17
    

    View Slide

11. DDD >No longer have composite
    UI/other concerns polluting
    our domain
    >Disconnects our domain
    model
    >Can better enforce
    consistency boundaries
    >Further reading:
    http://dddcommunity.org/library/verno
    n_2011/
    August 17
    

    View Slide

12. Abstraction >Removed the potential foot-
    gun of complex EF queries
    >Humans struggle with DSLs
    >Can write tailored, specific
    queries that suit individual
    demands
    >But what about that type
    safety we just gave up?
    >Well…
    August 17
    

    View Slide

13. The Codes, Part
    Three:
    

    View Slide

14. Thank You!
    @_AndrewB
    https://github.com/andrewabest
    

    View Slide

15. View Slide