1.
How a large corporation used
Domain-Driven Design
to replace a loyalty system

2.
Kacper Gunia
Independent consultant & Trainer
DomainCentric.net
@ddd_london
@cakper

3.
The Rescue Mission
@cakper

4.
The backlog
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5.
Event Storming
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6.
Microservices
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7.
Suboptimal boundaries
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8.
Teams distributed
across the globe
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9.
New and shiny
technologies
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10.
Skill Gap
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11.
So what did
we learn?
@cakper

12.
Let people learn
and make mistakes
@cakper

13.
Facilitate learning
→ Practice deliberately
→ Vary the assignments
→ Give access to resources
→ Explore solutions, show options
→ Collaborate, evaluate and conclude
@cakper

14.
Increase throughput and
reduce work in progress
@cakper

15.
Work with Conway's law
@cakper

16.
Technology is cool
@cakper

17.
Delivering value is cooler
@cakper

18.
Functional programming
is just a tool
@cakper

19.
Find helpful boundaries
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20.
It didn't
matter!
@cakper

21.
Can we deliver software?
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22.
Hell Yes!
@cakper

23.
The Legacy Rewrite
@cakper

24.
Legacy is great!
@cakper

25.
Context Map
@cakper

26.
C4 Model: System Context Diagram1
1
Simon Brown, https://c4model.com/

27.
Big Picture Event Storming
@cakper

28.
Ubiquitous Langugage
of legacy
@cakper

29.
Impact Mapping 2
2
Gojko Adzic, https://www.impactmapping.org/

30.
Story mapping3
3
https://manifesto.co.uk/user-story-mapping/

31.
Design Level Event Storming4
4
Alberto Brandolini, Introducing EventStorming

32.
Prototype it!
@cakper

33.
Model Exploration Whirlpool5
5
Eric Evans, http://domainlanguage.com/ddd/whirlpool/

34.
Leverage existing
specs and tests
@cakper

35.
Consider both technical
and social constraints
@cakper

36.
Constantly monitor and
evaluate your choices
@cakper

37.
Consistency is
a business problem
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38.
Microservices
@cakper

39.
Event Sourcing
@cakper

40.
Learning curve
@cakper

41.
Events are explicit
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42.
Data migration
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43.
Projections
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44.
Testing
@cakper

45.
Living Documentation
@cakper

46.
Design for replayability
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47.
(Do not)
Roll your own
Event Store
@cakper

48.
Summary
→ Legacy is a source of requirements, not design
→ Use strategic patterns to understand the system
→ Create and evolve tactical design iteratively
→ Monitor the sociotechnical architectrue
@cakper

49.
Thank you!
Training: Strategic DDD
& Sociotechnical Architecture
NYC 18th - 19th November 2019
@cakper / DomainCentric.net