Turns out Domain-Driven Design works not only for cargo shipping. I’d like to share the story of Plexop. Plexop is a large-scale marketing system that spans dozens of different business domains, from management of ad spaces to sellers’ commissions. To implement Plexop we had little resources and a very short time to market. That’s why we embraced DDD from day one, and boy did it pay out. I'll show how DDD allowed us to tackle complexities, talk on strategies for defining service boundaries that we tried, and of course, the things that we had to learn the hard way - by making our own mistakes.

1. 7 Years of Domain-Driven Design:
Tackling Complexity in Marketing Systems
Vladik Khononov
AMSTERDAM | MAY 8-9, 2018

2. Vladik Khononov
IAF Malam Team MSN-IL Cellcom Internovus
Twitter: @vladikk
Blog: vladikk.com

3. Vladik Khononov
IAF Malam Team MSN-IL Cellcom Internovus
Twitter: @vladikk
Blog: vladikk.com

4. AGENDA

5. PART 1
5 BOUNDED
CONTEXTS

6. PART 1
5 BOUNDED
CONTEXTS
PART 2
PRACTICAL
ADVICE

8. YAY!!!

10. Your Product

11. Your Product Marketing
Strategy

12. Your Product Marketing
Strategy
Creatives

13. Your Product Marketing
Strategy
Creatives Campaigns

14. Your Product Marketing
Strategy
Creatives Campaigns Sales
Agents

15. Your Product Marketing
Strategy
Creatives Campaigns Sales
Agents
Optimization

16. Your Product Marketing
Strategy
Creatives Campaigns Sales
Agents
OptimizationProfits

17. THE FIRST
BOUNDED CONTEXT
01

18. VER 1.0
Media Buying

19. VER 1.0
Media Buying
Creatives Catalog

20. VER 1.0
Media Buying
Creatives Catalog
Campaign Management

21. 🤔

23. Very nice!

24. Aggregates everywhere!!!

25. Aggregates everywhere!!!
Creative
Agency
Advertiser
Publisher
Website
Placement
Ad Zone
Ad Type
Target Market
Group
Zone Type
Funnel
Contract
Budget Unit
Campaign

26. The Bounded Context
Creative
Agency
Advertiser
Publisher
Website
Placement
Ad Zone
Ad Type
Target Market
Group
Zone Type
Funnel
Contract
Budget Unit
Audience

27. Domain Model
Service / Application Layer
Presentation
Infrastructure
Anemic!

28. Domain Model
Service / Application Layer
Presentation
Infrastructure
Anemic!
Behaviour

29. Imperfect architecture
“QA is for cowards”
BUT IT WORKED!

30. UBIQUITOUS LANGUAGE

31. Domain ExpertSoftware Developer
Has no experience in online marketing
Nice people!

32. Smooth communication
Strong grasp of the business domain
Working software
Aggressive time to market

33. UbiquitousLanguage Anemic Domain Model

34. Leads Sales AgentsAds

35. Leads CRM

36. Leads CRM Categorize

37. Leads CRM Categorize Desk
Desk
Desk
Sales Agents
Sales Agents
Sales Agents

38. Leads CRM Categorize Desk
Desk
Desk
Sales Agents
Sales Agents
Sales Agents
Clients’ Systems

40. Lead qualification
Agent qualification
Agents’ commissions

41. THE CRM
BOUNDED CONTEXT
02

42. UbiquitousLanguage Anemic Domain Model

43. Creative
Agency
Publisher
Website
Advertiser
Ad Zone
Ad Type
Target Market
Group
Zone Type
Funnel
Contract
Budget Unit
Audience
Group
Desk
Qualification
Assessment
Organization Unit
Assignment
Rank
Message
On-site Activity
Placement Visit Brand
Marketing Lead
CRM Lead
Marketing CRM Campaign

44. Domain ExpertSoftware Developer
…. Lead ….
…. Campaign…

47. BOUNDED CONTEXTS
PROTECT THE LANGUAGE
AGGREGATES PROTECT
CONSISTENCY OF DATA

48. Creative
Agency
Publisher
Website
Advertiser
Ad Zone
Ad Type
Target Market
Group
Zone Type
Funnel
Contract
Budget Unit
Audience
Group
Desk
Qualification
Assessment
Organization Unit
Assignment
Rank
Message
On-site Activity
Placement Visit Brand
Marketing Lead
CRM Lead
Marketing CRM Campaign

49. Creative
Agency
Publisher
Website
Advertiser
Ad Zone
Ad Type
Target Market
Group
Zone Type
Funnel
Contract
Budget Unit
Audience
Placement Visit
Lead
Campaign
Marketing
Group
Desk
Qualification
Assessment
Organization Unit
Assignment
Rank
Message
On-site Activity
Brand
Lead
Campaign
CRM

50. Aggregates will:
• Protect transactional boundaries
• Encompass business logic and invariants
Domain
Service / Application Layer
Presentation
Infrastructure

51. Aggregates will:
• Protect transactional boundaries
• Encompass business logic and invariants
Domain
Service / Application Layer
Presentation
Infrastructure
Domain
Service / Application Layer

55. Stored
procedures???

56. Group
Desk
Qualification
Assessment
Organization Unit
Assignment
Rank
Message
On-site Activity
Brand
Lead
Campaign
Lead

57. L e a d
CRM Team DBA Team

59. Inconsistent models
No shared understanding
Duplication of knowledge
Went out of sync quickly
NIGHTMARE

60. Wasn’t delivered on time
Production issues
Data corruption
Thrown away and reimplemented

61. Wasn’t delivered on time
Production issues
Data corruption
Thrown away and reimplemented

62. Wasn’t delivered on time
Production issues
Data corruption
Thrown away and reimplemented

63. Wasn’t delivered on time
Production issues
Data corruption
Thrown away and reimplemented

64. UbiquitousLanguage
Domain Model
BoundedContexts
Protect w/ Implement as

65. UbiquitousLanguage
Domain Model
BoundedContexts
Protect w/ Implement as
…Dude, where are Sub-Domains?

66. Not all of a large system will be well designed
“Eric Evans

67. THE CRUNCHERS
BOUNDED CONTEXT
03

68. Marketing CRM Analysis
Customer
Events
Marketing CRM

69. Marketing
CRM
Analysis
Customer
Events
Event
Crunchers

70. Competitive advantage? - No
Off-the-shelve solution? - No
=> Supporting sub-domain

71. Layered Architecture
Transaction Script
Worked
…. for a while

72. Customer
Events
Event
Crunchers
Marketing
CRM
Analysis
Flag Flag
Calculated fields

73. Marketing
CRM
Analysis
Customer
Events
Event
Crunchers

74. Customer
Events
Event Crunchers
(BBOM)
CRM
Marketing
Analysis

75. Customer
Events
Event
Crunchers
(Event Sourced)
CRM
Marketing
Analysis

76. THE BONUSES
BOUNDED CONTEXT
04

77. Sales Commissions Reports

78. Competitive advantage? - No
Off-the-shelve solution? - No
=> Supporting sub-domain

79. Active Record
Service / Application Layer
Presentation
Infrastructure

80. Sales Commissions Reports
Let’s try different percentages
What if the percentage could be a function
of a price?
No, what if the percentage is a function of
number of sales?
No, no, the percentage will be a function
both of number of sales and sale amount
And another upgrade if there are more
than Y sales per week!
But we will upgrade the percentage if
there are more than X sales per month!

81. Active Record
Service / Application Layer
Presentation
Infrastructure
BIG BALL OF MUD

82. Event Sourced Domain Model
Service / Application Layer
Presentation
Infrastructure
BIG BALL OF MUD

83. Active Record
Service / Application Layer
Presentation
Infrastructure
Transaction Script
Service / Application Layer
Presentation
Infrastructure
Event Crunchers Bonuses

84. Active Record
Service / Application Layer
Presentation
Infrastructure
Transaction Script
Service / Application Layer
Presentation
Infrastructure
Event Crunchers Bonuses
UbiquitousLanguage

85. Event Sourced Domain Model
Service / Application Layer
Presentation
Infrastructure
Event Sourced Domain Model
Service / Application Layer
Presentation
Infrastructure
Event Crunchers Bonuses
UbiquitousLanguage

86. UbiquitousLanguage
Core
BoundedContexts
Protect by
decomposing to
Identify
Domains
Domain Model
Supporting
Generic
AR / TS
Adopt
Implement as

87. THE MARKETING HUB
BOUNDED CONTEXT
05

88. Leads Marketing Hub
Client
Client
Client

89. Competitive advantage? - Yes
=> Core Domain

90. Event Sourced Domain Model
CQRS
Microservices

91. Micro
Service
Micro
Service
Micro
Service
Micro
Service

92. Aggregate
Aggregate
Aggregate
Aggregate

93. Aggregate
Aggregate
Aggregate
Aggregate
Event
Sourced
Aggregate

94. Aggregate
Aggregate
Aggregate
Aggregate
Event
Sourced
Aggregate

95. Event Sourced Domain Model
CQRS
Microservices

96. Aggregate
Aggregate
Aggregate
Aggregate
Event
Sourced
Aggregate

97. TECHNICAL
COMPLEXITY
BUSINESS
COMPLEXITY>

98. Aggregate
Aggregate
Aggregate
Aggregate
Event
Sourced
Aggregate

99. Marketing
Bonuses
U D
CRM
U
D
Marketing
Hub
U U
D
D
Event
Crunchers
U
D
U D

100. WHAT
WE HAVE
L E A R N E D

101. UBIQUITOUS
LANGUAGE
01

102. Ubiquitous Language:
The Core Domain of Domain-Driven Design

103. UBIQUITOUS
LANGUAGE
DOCUMENTS
TESTS
JIRA
>

104. Marketing
Ubiquitous Language
Business goals achieved

105. Marketing
Ubiquitous Language
Business goals achieved
CRM
Ubiquitous Language
Production issues
Long and painful refactoring

106. Marketing
Ubiquitous Language
Business goals achieved
CRM
Ubiquitous Language
Production issues
Long and painful refactoring
Event Crunchers
Ubiquitous Language
Big ball of mud

107. Marketing
Ubiquitous Language
Business goals achieved
CRM
Ubiquitous Language
Production issues
Long and painful refactoring
Event Crunchers
Ubiquitous Language
Big ball of mud
Bonuses
Ubiquitous Language
Refactored in time

108. Invest in the Ubiquitous Language early on.

109. Marketing
Ubiquitous Language
Business goals achieved
CRM
Ubiquitous Language
Production issues
Long and painful refactoring
Event Crunchers
Ubiquitous Language
Big ball of mud
Bonuses
Ubiquitous Language
Refactored in time

110. Cheap!

111. DOMAIN
TYPES
02

112. Core
Supporting
Generic

113. Generic Domain Adopt / Buy
Supporting Domain Active Record / Transaction Script
Core Domain Domain Model / Event Sourcing

114. COMPANIES CHANGE, EVOLVE, REINVENT THEMSELVES
DOMAINS' TYPES CAN CHANGE ACCORDINGLY

115. SUPPORTING ➤ CORE
• Event Crunchers
• Bonuses

116. SUPPORTING ➤ CORE
• Event Crunchers
• Bonuses
SUPPORTING ➤ GENERIC
• Creative Catalog

117. SUPPORTING ➤ CORE
• Event Crunchers
• Bonuses
SUPPORTING ➤ GENERIC
• Creative Catalog
CORE ➤ GENERIC
• Lead Evaluation System

118. SUPPORTING ➤ CORE
• Event Crunchers
• Bonuses
SUPPORTING ➤ GENERIC
• Creative Catalog
CORE ➤ GENERIC
• Lead Evaluation System
CORE ➤ SUPPORTING
• Marketing Hub

119. SUPPORTING ➤ CORE
• Event Crunchers
• Bonuses
SUPPORTING ➤ GENERIC
• Creative Catalog
CORE ➤ GENERIC
• Lead Evaluation System
CORE ➤ SUPPORTING
• Marketing Hub
GENERIC ➤ CORE
• AWS

120. Generic Domain Adopt / Buy
Supporting Domain Active Record / Transaction Script
Core Domain Domain Model / Event Sourcing

121. Generic DomainAdopt / Buy
Supporting DomainActive Record / Transaction Script
Core DomainDomain Model / Event Sourcing

122. Less waste
Dialog with the business
IMPLEMENTATION DESIGN ➤ DOMAIN TYPE

123. • Questionable competitive edge?
BUSINESS COMPLEXITY ≠ DOMAIN TYPE?

124. • Questionable competitive edge?
• Accidental “business” complexity?
BUSINESS COMPLEXITY ≠ DOMAIN TYPE?

125. • Questionable competitive edge?
• Accidental “business” complexity?
• Unexpected competitive edge?
BUSINESS COMPLEXITY ≠ DOMAIN TYPE?

126. Generic DomainAdopt / Buy
Supporting DomainActive Record / Transaction Script
Core DomainDomain Model / Event Sourcing
IMPLEMENTATION DESIGN ➤ DOMAIN TYPE

127. IMPLEMENTATION
STRATEGIES
03

128. How to Model the Business Logic?
Transaction Script
Active Record
Domain Model
Event Sourced Domain Model

129. MONEY? DEEP ANALYTICS? AUDIT LOG?
Event Sourced Domain Model

130. MONEY? DEEP ANALYTICS? AUDIT LOG?
Event Sourced Domain Model
COMPLEX BUSINESS LOGIC?
Domain Model

131. MONEY? DEEP ANALYTICS? AUDIT LOG?
Event Sourced Domain Model
COMPLEX BUSINESS LOGIC?
Domain Model
COMPLEX DATA STRUCTURES?
Active Record

132. MONEY? DEEP ANALYTICS? AUDIT LOG?
Event Sourced Domain Model
COMPLEX BUSINESS LOGIC?
Domain Model
COMPLEX DATA STRUCTURES?
Active Record
SIMPLE LOGIC, SIMPLE DATA STRUCTURES?
Transaction Script

133. Transaction Script
Active Record
Domain Model
Event Sourced Domain Model

134. MAPPING ARCHITECTURAL PATTERNS
Event Sourced Domain Model ➤ CQRS
Domain Model ➤ Hexagonal Architecture
Active Record ➤ Layered Architecture
Transaction Script ➤ “Keep it simple” Architecture

135. Transaction Script
Active Record
Domain Model
Event Sourced Domain Model

136. PAIN?
BUSINESS CHANGED?
DOMAIN TYPE CHANGED?
REVISE IMPLEMENTATION STRATEGY?
➤

137. Transaction Script
Active Record
Domain Model
Event Sourced Domain Model

138. 04
BOUNDED
CONTEXTS

139. Creative
Agency
Publisher
Website
Advertiser
Ad Zone
Ad Type
Target Market
Group
Zone Type
Funnel
Contract
Budget Unit
Audience
Placement Visit
Lead
Campaign
Marketing
Group
Desk
Qualification
Assessment
Organization Unit
Assignment
Rank
Message
On-site Activity
Brand
Lead
Campaign
CRM
LINGUISTIC BOUNDARIES

140. Bonuses
Event
Crunchers
DOMAIN-BASED BOUNDARIES

141. AGGREGATE-BASED BOUNDARIES
Aggregate
Aggregate
Aggregate
Aggregate

142. L e a d
SUICIDAL BOUNDARIES

144. Finding service boundaries is really damn
hard… There is no flowchart!
“Udi Dahan

145. THERE ARE GOING TO BE MISTAKES
ACCEPT IT, AND DON’T MAKE FATAL ONES

146. START WITH BIGGER BOUNDARIES
DECOMPOSE LATER, AS YOU GAIN KNOWLEDGE

147. THE LESS YOU KNOW ABOUT THE DOMAIN -
THE WIDER THE INITIAL BOUNDARIES ARE

148. Aggregate
Aggregate
Aggregate
Aggregate
Event
Sourced
Aggregate

149. Marketing
Creative
Agency
Publisher
Website
Advertiser
Ad Zone
Ad Type
Target Market
Group
Zone Type
Funnel
Contract
Budget Unit
Audience
Placement Visit
Lead
Campaign

150. Campaigns
Creative
Ad Type
Agency
Publisher
Website
Zone Type
ContractBudget Unit
Impression
Visit
Lead
Advertiser
Target MarketFunnel
Audience
Placement
Campaign
Creative Catalog
Publishers
Events

151. START WITH BIGGER BOUNDARIES
DECOMPOSE AS YOU GAIN DOMAIN KNOWLEDGE

152. 05
SUMMARY

153. 1. Ubiquitous Language is not optional
2. Domain Types change. Embrace these changes
3. Learn the ins and outs of the four patterns of modeling business logic
4. Start with bigger boundaries, and divide as you gain domain knowledge

154. UbiquitousLanguage
BoundedContexts
Protect by
decomposing to
Design
Implementation
Core
Supporting
Generic
Domain Model
AR / TS
Adopt
Confirm w/
Business

155. UbiquitousLanguage
BoundedContexts
Protect by
decomposing to
Design
Implementation
Core
Supporting
Generic
Domain Model
AR / TS
Adopt
Confirm w/
Business

156. UbiquitousLanguage
BoundedContexts
Protect by
decomposing to
Design
Implementation
Core
Supporting
Generic
Domain Model
AR / TS
Adopt
Confirm w/
Business

157. UbiquitousLanguage
BoundedContexts
Protect by
decomposing to
Design
Implementation
Core
Supporting
Generic
Domain Model
AR / TS
Adopt
Confirm w/
Business

158. UbiquitousLanguage
BoundedContexts
Protect by
decomposing to
Design
Implementation
Core
Supporting
Generic
Domain Model
AR / TS
Adopt
Confirm w/
Business

159. Creative
Agency
Advertiser
Publisher
Website
Placement
Ad Zone
Ad Type
Target Market
Group
Zone Type
Funnel
Contract
Budget Unit
Campaign
Aggregates everywhere!!!

160. UbiquitousLanguage
BoundedContexts
Protect by
decomposing to
Design
Implementation
Core
Supporting
Generic
Domain Model
AR / TS
Adopt
Confirm w/
Business
Ubiquitous Language Everywhere!!!

161. THANK YOU!
@vladikk vladikk.com