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