This document introduces Domain-Driven Design (DDD). DDD is an approach to software development that connects implementation to an evolving model of the complex domain. It involves building a shared understanding of the domain with experts and designing the software around the domain model. Key aspects of DDD include developing a meaningful domain model, defining bounded contexts, using entities, value objects, aggregates, factories, repositories, services, and domain events to structure the software architecture. The document provides an overview of these building blocks and encourages iterative modeling in an agile fashion.

1. Introduction to DDD
Adam Štipák | @new_POPE | rekurzia.sk

2. Who I am?
Adam Štipák
@new_POPE
rekurzia.sk
● since 2006
● Sven Creative
● Sygic
● Diagnose.me
● and other “secret” projects

3. What is DDD?
“is an approach to software development for complex needs
by connecting the implementation to an evolving model”
- wikipedia.org

4. ● Useful and meaningful model of its Domain
● Domain Experts contribute to software design
● Better user experience
● Clear boundaries
● Better architecture organization
● Iterative and continuous modeling in an Agile fashion
● better tools, both strategic and tactical design
Why DDD?

5. Architectural styles - old layered architecture

6. Architectural styles - MVC

7. Architectural styles - Hexagonal architecture

8. The dependecy inversion principle
“High-level modules should not depend on low-level modules. Both should depend
on abstractions.
Abstractions should not depend on details. Details should depend on
abstractions.”
- Robert C. Martin

9. Ubiquitous language
“When we recieve a new order, system sends a
notification”

10. Ubiquitous language
What is the new order?

11. Bounded context

12. Building blocks

13. Value Objects
● Immutable
● “comparable”

14. Entities
● Identifiable
● Consistent
● Avoid ANEMIC MODEL
○ setSong(newSong)
○ replaceSong(newSong)

15. Aggregates
● lists, maps, etc
● order, clinic visit, playlist
is a cluster of domain objects that can be treated as a
single unit.
… says Martin Fowler

16. Factories
● creates something
● create(...)

17. Repositories
● Collection oriented
○ get(ID), add(), addAll(), remove()
● Persistent oriented
○ get(ID), save(), saveAll(), ...

18. Services
● stateless
● singleton (not Singleton pattern)
○ e.g. ne instance in DI container
● SRP!

19. Domain Events
● contains data
● immutable
E.g.
● born
● song replaced
● song on cassette was cleared

20. Resources
● The blue book
● The red book
● Domain Driven Design Quickly
● Domain-Driven Design in PHP

21. ???Questions ???
Adam Štipák | @new_POPE | rekurzia.sk

22. Thank you!
Adam Štipák | @new_POPE | rekurzia.sk