7 Years of Domain-Driven Design

It turns out that domain-driven design works for more than just cargo shipping. Vladik Khononov shares his experience using the domain-driven design methodology at Plexop, a large-scale marketing system that spans over a dozen of different business domains, from the management of advertising spaces to sales agents’ commissions. Vladik and his team had very limited resources and a very short time to market to implement Plexop. He explains how DDD allowed them to manage complexities, discusses different strategies for defining context boundaries, and of course, details the lessons that they learned the hard way.

Transcript

1. vladikk 7 YEARS OF DDD or Tackling Complexity in
 Large Scale Marketing Systems
2. YAY!!!
3. @vladikk vladikk.com Internovus
4. vladikk PART 2 
 5 PRACTICAL ADVICES PART 1
 5 BOUNDED CONTEXTS
6. vladikk Your Product Marketing
 Strategy Creatives Campaigns Sales
 Agents Optimization Profits
7. vladikk THE FIRST BOUNDED CONTEXT 01
8. vladikk Media Buying Creatives Catalog Campaign Management VER 1.0
9. vladikk
10. vladikk
11. Very nice!!!1
12. vladikk Aggregates everywhere!!!
13. vladikk Aggregates everywhere!!! Creative Agency Advertiser Publisher Website Placement Ad Zone Ad Type Target Market Group Zone Type Funnel Contract Budget Unit Campaign
14. vladikk The Bounded Context Creative Agency Advertiser Publisher Website Placement Ad Zone Ad Type Target Market Group Zone Type Funnel Contract Budget Unit Audience
15. vladikk Domain Model Service / Application Layer Presentation Infrastructure Anemic! Behaviour
16. vladikk Imperfect architecture “QA is for cowards” BUT IT WORKED!
17. vladikk UBIQUITOUS LANGUAGE
18. vladikk Domain Experts Software Developers No experience in online marketing Nice people!
19. vladikk Smooth communication Strong grasp of the business domain Working software Aggressive time to market
20. vladikk Ubiquitous Language Anemic Domain Model
21. vladikk Leads Sales Agents Ads
22. vladikk Leads CRM Categorize Desk Desk Desk Sales Agents Sales Agents Sales Agents
23. Leads CRM Categorize Desk Desk Desk Sales Agents Sales Agents Sales Agents Clients’ Systems
24. vladikk
25. vladikk Lead qualification Agent qualification Agents’ commissions
26. vladikk THE CRM BOUNDED CONTEXT 02
27. vladikk Ubiquitous Language Anemic Domain Model
28. vladikk 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 Campaign CRM Campaign
29. vladikk Domain Experts Software Developers …. Lead …. …. Campaign…
30. vladikk
32. vladikk BOUNDED CONTEXTS PROTECT THE LANGUAGE AGGREGATES PROTECT CONSISTENCY OF DATA
33. vladikk 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 Campaign CRM Campaign
34. vladikk 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
35. vladikk Aggregates will:
 • Protect transactional boundaries
 • Encompass business logic and invariants Domain Service / Application Layer Presentation Infrastructure
36. vladikk Aggregates will:
 • Protect transactional boundaries
 • Encompass business logic and invariants Domain Service / Application Layer Presentation Infrastructure Domain Service / Application Layer
38. vladikk
40. vladikk Stored procedures???
41. vladikk Group Desk Qualification Assessment Organization Unit Assignment Rank Message On-site Activity Brand Lead Campaign Lead
42. L e a d CRM Team DBA Team
44. vladikk Inconsistent models No shared understanding Duplication of knowledge Went out of sync quickly NIGHTMARE
45. vladikk Wasn’t delivered on time Production issues Data corruption Thrown away and reimplemented
46. vladikk Ubiquitous Language Domain Model Bounded Contexts Protect w/ Implement as
47. Not all of a large system will be well designed “ Eric Evans
48. vladikk THE CRUNCHERS BOUNDED CONTEXT 03
49. vladikk Marketing CRM Analysis Customer Events Marketing CRM
50. vladikk Marketing CRM Analysis Customer Events Event Crunchers
51. vladikk Competitive advantage? - No Off-the-shelve solution? - No => Supporting sub-domain
52. vladikk Layered Architecture Transaction Script Worked …. for a while
53. vladikk Customer Events Event Crunchers Marketing CRM Analysis Flag Flag Calculated fields
54. vladikk
55. vladikk Marketing CRM Analysis Customer Events Event Crunchers
56. vladikk Customer Events Event Crunchers (BBOM) CRM Marketing Analysis
57. vladikk Customer Events Event Crunchers (Event Sourced) CRM Marketing Analysis
58. vladikk THE BONUSES BOUNDED CONTEXT 04
59. vladikk Sales Commissions Reports
60. vladikk Competitive advantage? - No Off-the-shelve solution? - No => Supporting sub-domain
61. vladikk Active Record Service / Application Layer Presentation Infrastructure
62. vladikk 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!
63. vladikk Active Record Service / Application Layer Presentation Infrastructure BIG BALL OF MUD
64. vladikk Event Sourced Domain Model Service / Application Layer Presentation Infrastructure BIG BALL OF MUD
65. vladikk Active Record Service / Application Layer Presentation Infrastructure Transaction Script Service / Application Layer Presentation Infrastructure Event Crunchers Bonuses Ubiquitous Language
66. vladikk Ubiquitous Language Core Bounded Contexts Protect by
 decomposing to Identify Domains Domain Model Supporting Generic AR / TS Adopt Implement as
67. vladikk THE MARKETING HUB BOUNDED CONTEXT 05
68. vladikk Leads Marketing Hub Client Client Client
69. vladikk Competitive advantage? - Yes => Core Domain
70. vladikk Event Sourced Domain Model CQRS Microservices
71. vladikk Micro
 Service Micro
 Service Micro
 Service Micro
 Service
72. vladikk Aggregate Aggregate Aggregate Aggregate
73. vladikk Aggregate Aggregate Aggregate Aggregate Event Sourced
 Aggregate
74. vladikk Aggregate Aggregate Aggregate Aggregate Event Sourced
 Aggregate
75. vladikk Event Sourced Domain Model CQRS Microservices
76. vladikk Aggregate Aggregate Aggregate Aggregate Event Sourced
 Aggregate
77. vladikk TECHNICAL COMPLEXITY BUSINESS COMPLEXITY >
78. vladikk Aggregate Aggregate Aggregate Aggregate Event Sourced
 Aggregate
79. Marketing Bonuses U D CRM U D Marketing
 Hub U U D D Event Crunchers U D U D
80. WHAT
 WE HAVE L E A R N E D
81. vladikk UBIQUITOUS LANGUAGE 01
82. vladikk UBIQUITOUS LANGUAGE THE CORE DOMAIN OF DOMAIN-DRIVEN DESIGN
83. vladikk 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
84. vladikk Invest in the Ubiquitous Language early on
85. vladikk 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
86. vladikk Cheap!
87. vladikk DOMAIN TYPES 02
88. vladikk Core Supporting Generic
89. vladikk Generic Domain Adopt / Buy Supporting Domain Active Record / Transaction Script Core Domain Domain Model / Event Sourcing
90. vladikk COMPANIES CHANGE, EVOLVE, REINVENT THEMSELVES DOMAINS' TYPES CHANGE ACCORDINGLY
91. vladikk SUPPORTING ➤ CORE • Event Crunchers • Bonuses SUPPORTING ➤ GENERIC • Creative Catalog CORE ➤ GENERIC • Lead Evaluation System CORE ➤ SUPPORTING • Marketing Hub GENERIC ➤ CORE • AWS
92. vladikk Generic Domain Adopt / Buy Supporting Domain Active Record / Transaction Script Core Domain Domain Model / Event Sourcing
93. vladikk Generic Domain Adopt / Buy Supporting Domain Active Record / Transaction Script Core Domain Domain Model / Event Sourcing
94. vladikk Less waste Dialog with the business IMPLEMENTATION DESIGN ➤ DOMAIN TYPE
95. vladikk • Questionable competitive edge? • Accidental “business” complexity? • Unexpected competitive edge? BUSINESS COMPLEXITY ≠ DOMAIN TYPE?
96. vladikk Generic Domain Adopt / Buy Supporting Domain Active Record / Transaction Script Core Domain Domain Model / Event Sourcing IMPLEMENTATION DESIGN ➤ DOMAIN TYPE
97. vladikk IMPLEMENTATION STRATEGIES 03
98. vladikk How to Model the Business Logic?
99. vladikk How to Model the Business Logic? Transaction Script (PoEAA) Active Record (PoEAA) Domain Model (PoEAA + DDD) Event Sourced Domain Model
100. vladikk 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
101. vladikk MAPPING ARCHITECTURAL PATTERNS Event Sourced Domain Model ➤ CQRS Domain Model ➤ Hexagonal Architecture Active Record ➤ Layered Architecture Transaction Script ➤ “Keep it simple” Architecture
102. vladikk MAPPING ARCHITECTURAL PATTERNS Event Sourced Domain Model ➤ CQRS Domain Model ➤ Hexagonal Architecture Active Record ➤ Layered Architecture Transaction Script ➤ “Keep it simple” Architecture
103. vladikk Transaction Script Active Record Domain Model Event Sourced Domain Model
104. vladikk PAIN? BUSINESS CHANGED? DOMAIN TYPE CHANGED? REVISE IMPLEMENTATION STRATEGY? ➤
105. vladikk Transaction Script Active Record Domain Model Event Sourced Domain Model
106. vladikk CQRS 04
107. vladikk Event Sourcing ➤ CQRS
108. vladikk EVENT SOURCING BUSINESS DOMAIN MODELING PATTERN CQRS ARCHITECTURAL PATTERN FOR REPRESENTING DATA IN DIFFERENT PERSISTENT MODELS
109. vladikk Transaction Script Active Record Domain Model } Can benefit from CQRS and State-Based Projections
110. vladikk RDBMS Search index Files
 storage Projection
 Engine Projected
 Model Projected
 Model Changes Application Query Query Commit
111. vladikk COMMAND QUERY 
 RESPONSIBILITY SEGREGATION?
112. vladikk Did command succeed or fail? If failed - why? What are the outcomes? } Can be delivered asynchronously through queries … but why?
113. vladikk Write
 Model Projection Projection Projection
 Engine Projected
 Model Projected
 Model Changes Application Client Command
 Execution Result Query
114. vladikk 05 BOUNDED CONTEXTS
115. vladikk 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
116. vladikk Bonuses Event Crunchers DOMAIN-BASED BOUNDARIES
117. vladikk AGGREGATE-BASED BOUNDARIES Aggregate Aggregate Aggregate Aggregate
118. vladikk L e a d SUICIDAL BOUNDARIES
119. vladikk
120. vladikk BOUNDED CONTEXTS ARE NOT MICROSERVICES
121. vladikk BOUNDED CONTEXTS PROTECT INTEGRITY OF A UBIQUITOUS LANGUAGE
122. vladikk 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 Campaign CRM Campaign
123. vladikk MICROSERVICES DECOMPOSITION OF A SYSTEM INTO LOOSELY COUPLED COMPONENTS BOUNDED CONTEXTS PROTECT INTEGRITY OF A UBIQUITOUS LANGUAGE
124. vladikk Micro
 Service Micro
 Service Micro
 Service Micro
 Service
125. Finding service boundaries is really damn hard… There is no flowchart! “ Udi Dahan
126. vladikk THERE ARE GOING TO BE MISTAKES ACCEPT IT AND DON’T MAKE FATAL ONES
127. vladikk THE LESS YOU KNOW ABOUT THE DOMAIN THE WIDER THE INITIAL BOUNDARIES START WITH BIGGER BOUNDARIES DECOMPOSE LATER, AS YOU GAIN KNOWLEDGE
128. vladikk Aggregate Aggregate Aggregate Aggregate Event Sourced
 Aggregate
129. vladikk Marketing Creative Agency Publisher Website Advertiser Ad Zone Ad Type Target Market Group Zone Type Funnel Contract Budget Unit Audience Placement Visit Lead Campaign
130. vladikk Campaigns Creative Ad Type Agency Publisher Website Zone Type Contract Budget Unit Impression Visit Lead Advertiser Target Market Funnel Audience Placement Campaign Creative Catalog Publishers Events
131. vladikk START WITH BIGGER BOUNDARIES DECOMPOSE AS YOU GAIN DOMAIN KNOWLEDGE
132. vladikk 1. Ubiquitous Language is not optional 2. Domain Types change. Embrace these changes to achieve resilient design 3. Learn the ins and outs of the four patterns of modeling business logic 4. Use CQRS to represent the same data in multiple models 5. Bounded Contexts are not Microservices. Always start with bigger boundaries, but decompose further as you gain domain knowledge
133. vladikk SUMMARY
134. vladikk Ubiquitous Language Bounded Contexts Protect by
 decomposing to Design
 Implementation Core Supporting Generic Domain Model AR / TS Adopt Confirm w/
 Business
135. vladikk Ubiquitous Language Bounded Contexts Protect by
 decomposing to Design
 Implementation Core Supporting Generic Domain Model AR / TS Adopt Confirm w/
 Business
136. vladikk Ubiquitous Language Bounded Contexts Protect by
 decomposing to Design
 Implementation Core Supporting Generic Domain Model AR / TS Adopt Confirm w/
 Business
137. vladikk Ubiquitous Language Bounded Contexts Protect by
 decomposing to Design
 Implementation Core Supporting Generic Domain Model AR / TS Adopt Confirm w/
 Business
138. vladikk Ubiquitous Language Bounded Contexts Protect by
 decomposing to Design
 Implementation Core Supporting Generic Domain Model AR / TS Adopt Confirm w/
 Business
139. vladikk Creative Agency Advertiser Publisher Website Placement Ad Zone Ad Type Target Market Group Zone Type Funnel Contract Budget Unit Campaign Aggregates everywhere!!!
140. vladikk Ubiquitous Language Bounded Contexts Protect by
 decomposing to Design
 Implementation Core Supporting Generic Domain Model AR / TS Adopt Confirm w/
 Business Ubiquitous Language Everywhere!!!
141. vladikk P.S.
142. vladikk
143. THANK YOU! @vladikk vladikk.com