This document discusses using the actor model with domain-driven design for reactive systems. It provides an overview of the actor model and how it relates to DDD. Key points include: - The actor model uses message passing between independent units called actors to build distributed, concurrent systems. - The actor model is well-suited for building reactive systems to handle high volumes of asynchronous data and messages. - DDD focuses on modeling the core domain and business logic, while actors and messaging enable rapid implementation in a clear and understandable way. - Together, the actor model and DDD support building systems that can respond quickly to changing business needs through loose coupling and isolation of concerns.

1. Using the Actor Model with
Domain-Driven Design (DDD) in
Reactive Systems
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2. @VaughnVernon
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3. Books
Consulting and Training
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4. Objects

5. 1973 - 2003

6. Cores Matter
More cores, not (much) faster cores

7. Threading Is Easy!

8. Threading Is Hard!

9. Actor Model
Alan Kay: “The big idea is messaging...”

10. Carl Hewitt, 1973

11. Jonas Bonér, Akka

12. Actors Are
Reactive

13. Reactive Is

14. Reactive Is

15. Reactive Is

16. Reactive Is

17. Why the Actor Model Now?
#IoT

18. Because Cores
88 / 200+ cores with Xeon Phi co-processors

19. Embrace
Latency

20. More
With
Less

21. Direct Asynchronous Messaging

22. Lock-Free, Share Nothing

23. Become:
Prepare for Next Message

24. Actor System

25. Actor Concurrency

26. How Many Actors?
50+
100+
1,000,000+

27. Typical Architecture

28. Complexity Stack

29. Simplicity Stack

30. Inventor of DDD

31. Essence of DDD

32. Context Mapping

33. Responding to Rapid
New Business Direction
DDD enables necessary
knowledge crunching
Actors and messages enables
rapid implementation and
clear understanding

34. Actors and DDD
Alan Kay: “The big idea is messaging...”
Alan Kay: “The Actor model retained more
of what I thought were the good
features of the object idea.”

35. Ubiquitous
Language
As Actors and messages...

37. Actor
Command Event
Actor
Command Event
Event Storming
Time
Use design-level storming

38. Aggregates
Transactional Consistency Boundary

39. Aggregate
● Immutable state object/record
Implementation
● Transition and replace state
upon command
● Emit corresponding event

40. Reactive Systems

41. Read: Designing Reactive Systems With The Actor Model (free O'Reilly book)
Watch:
Benefits Of The Actor Model For Cloud Computing: A Pragmatic Overview For Java Architects
(co-presented with Forrester Research)
Learn from experts: ask about our Embedded Lightbend Engineer (ELE) for
kickstarting your Reactive initiatives
More Resources You May Enjoy…

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Austin (TX) - October 18-20, 2017
reactivesummit.org

43. @VaughnVernon
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