How to Split a Monolith: Service Architecture & Domain-Driven Design (DDD)

SAP LevelUp Version

Transcript

1. How to Split a Monolith: Service Architecture & Domain-Driven Design (DDD) Joy Ebertz Sr Staff Engineer
2. Today’s agenda • What do I mean by Service Architecture? • Why Worry About Service Architecture? • What is Domain-Driven Design or DDD? • What is Layered Architecture? • Mapping Back to Services
3. What do I mean by Service Architecture? (In the context of this talk)
4. Request API Gateway Authz Service AuthN Rate Limiting App Services Business Capability Services Foundational Capability Services Logging Event Bus Secrets Management Service Discovery
5. Typical SOA Architecture Request API Gateway Authz Service AuthN Rate Limiting App Services Business Capability Services Foundational Capability Services Logging Event Bus Secrets Management Service Discovery
6. Typical SOA Architecture App Services Business Capability Services Foundational Capability Services
7. Why worry about Service Architecture?
10. Code Repetition
11. Code Repetition
12. Code Repetition
13. Hyper-localized Optimizations
14. Chaos
15. Chaos
16. Chaos
17. Chaos
19. FE BE
20. Domains/Bounded Contexts FE BE
21. Layers FE BE
22. What is Domain-Driven Design or (DDD)?
23. DDD is an approach to developing software for complex needs by deeply connecting the implementation to an evolving model of the core business concepts.
24. Since 2004
25. Business Value over Technical Strategy DDD Principles
26. DDD Principles Cross-functional Collaboration
27. over Point Solutions DDD Principles
28. Software Best Practices: Separation of Concerns DDD Principles
29. Software Best Practices: Simplicity. DDD Principles
30. DDD Principles
31. DDD Core Concepts • Domains and Subdomains
32. DDD Core Concepts • Domains and Subdomains • Bounded Contexts
33. DDD Core Concepts • Domains and Subdomains • Bounded Contexts • Ubiquitous Language
34. DDD Core Concepts • Domains and Subdomains • Bounded Contexts • Ubiquitous Language
35. Domains & Subdomains DDD Core Concepts Problem Space
36. Domains & Subdomains DDD Core Concepts
37. Domains & Subdomains DDD Core Concepts
38. Domains & Subdomains DDD Core Concepts
39. Domains & Subdomains DDD Core Concepts
40. Domains & Subdomains DDD Core Concepts
41. Domains & Subdomains DDD Core Concepts
42. Types of Subdomains: Core Subdomain
45. Types of Subdomains: Supporting Subdomain
47. Types of Subdomains: Generic Subdomain
49. API Gateway Authentication Service Authorization Service Logging/Monitoring Contacting Customers (Email/Phone) (Feature Flags and A/B Testing)
50. Core Subdomain Supporting Subdomain Generic Subdomain
51. Core Subdomain Supporting Subdomain Generic Subdomain
52. Core Subdomain Supporting Subdomain Generic Subdomain
53. Core Subdomain Supporting Subdomain Generic Subdomain
54. DDD Core Concepts • Domains and Subdomains • Bounded Contexts • Ubiquitous Language
57. Domains
59. Bounded Context
60. The problem space is defined by a domain which consists of one or more subdomains.
61. The problem space is defined by a domain which consists of one or more subdomains. The solution space is defined by a domain model which consists of one or more bounded contexts.
62. Characteristics of Bounded Contexts
63. Clear and Controlled Entry Points Bounded Context
64. Clear and Controlled APIs Bounded Context
65. Bounded Context
66. Bounded Context
67. Bounded Context
68. DDD Core Concepts • Domains and Subdomains • Bounded Contexts • Ubiquitous Language
69. Ubiquitous Language Domain Expert Marketing Developer
70. Ubiquitous Language Domain Expert Marketing Developer Application Code Test Code Specs and Documentation Discussions & whiteboarding
71. Subdomain Subdomain
72. What is a file?
73. Content Subdomain The container object that groups different versions of a piece of content and enables Box file- system capabilities. What is a file?
74. Content Subdomain Storage Subdomain The container object that groups different versions of a piece of content and enables Box file- system capabilities. A blob of customer-owned data identified by a uniq_name. What is a file?
75. Domains/Bounded Contexts FE BE
76. Layers FE BE
77. What is Layered Architecture?
78. Layered Architecture is a way of dividing up an architecture between front-end, middle tier and back-end logic to optimize for decoupling and re-use.
79. Application
80. Application Business Capability
81. Application Business Capability Foundational Capability
82. Application Business Capability Foundational Capability Infrastructure Services
83. Application Business Capability Foundational Capability Infrastructure Services
84. Backend For Frontend (BFF)
85. Your Servers Backend For Frontend (BFF)
86. Your Servers FE Engineers BE Engineers Backend For Frontend (BFF)
87. Your Servers FE Engineers BE Engineers Backend For Frontend (BFF)
88. Your Servers FE Engineers BE Engineers Backend For Frontend (BFF)
89. Backend For Frontend (BFF) Application Service FE Engineers
90. Application Service Application Service Application Service Backend For Frontend (BFF)
91. Application Service Application Service Application Service
93. Application Business Capability Foundational Capability Infrastructure Services
95. Business Capability Service
96. Physical Store Race Expo Website Buy Running Shoes
97. iPhone Buy Running Shoes
98. iPhone Buy Running Shoes
99. iPhone Buy Running Shoes Webapp
100. iPhone Buy Running Shoes Webapp
102. Application Business Capability Foundational Capability Infrastructure Services
106. Single Source of Truth
107. User Profile User Profile
108. User Profile User Billing
110. Application Business Capability Foundational Capability Infrastructure Services
112. Often Generic Subdomains
113. Mapping Back to Services
115. Application Service Application Service
116. Application Service Application Service Foundational Backend Service Business Capability Backend Service
117. Application Service Application Service Foundational Backend Service Business Capability Backend Service
118. Application Service Application Service Foundational Backend Service Business Capability Backend Service Backend Service
119. Typical SOA Architecture Request API Gateway Authz Service AuthN Rate Limiting App Services Business Capability Services Foundational Capability Services Logging Event Bus Secrets Management Service Discovery
120. Recap • Service Architecture • Domain-Driven Design or DDD • Layered Architecture • Mapping Back to Services Joy Ebertz @jkebertz Joy.Ebertz@split.io
121. Thank you!
122. Further Resources • Eric Evans’ classic DDD book that started it all (the ‘Blue Book’): Domain Driven Design: Tackling Complexity in the Heart of Software • Vaughn Vernon has a book a bit more on the practical side (the ‘Red Book’): Implementing Domain Driven Design • If you want something a bit shorter Vaughn Vernon also has a shortened version: Domain Driven Design Distilled • For another shorter, more reference driven option, Eric Evans also has: Domain Driven Design Reference • A former colleague recommends Scott Millett’s book: Patterns, Priciples, and Practices of Domain Driven Design DDD Books
123. • Getting Started with Domain Driven Design: http://www.informit.com/articles/article.aspx?p=1944876&seqNum=5 • Strategic Domain Driven Design with Context Mapping: https://www.infoq.com/articles/ddd- contextmapping/ • My blog post, A Brief Intro to Domain Driven Design: https://austinstartups.com/a-brief-intro- to-domain-driven-design-326cf1669bbc • Is Design Dead? https://www.martinfowler.com/articles/designDead.html • How Can Domain-driven design help with large scale agile development? http://www.ben- morris.com/how-can-domain-driven-design-help-with-large-scale-agile-development/ DDD Articles Further Resources
124. • Thoughtworks has a really great blog post about this topic: https://www.thoughtworks.com/insights/blog/well-factored-approach-securing-roi- your-service-investment-part-2 . Part 1 is here: https://www.thoughtworks.com/insights/blog/well-factored-approach-securing-roi-your- service-investment, but honestly most of the good material is in part 2. • The language in this one is a little bit different, but Mulesoft fundamentally talks about a lot of the same concepts: https://cloud.box.com/s/ggttm7wjsposhrcjxxzdmb3f4uxzp6mg • Another one by Mulesoft. This one doesn't directly talk about the horizontal splitting but does have a great diagram: https://www.linkedin.com/pulse/build-business-capabilities-apis- nial-darbey Layered Architecture Articles Further Resources
125. • This also covers a lot more material, but in their Identifying Services section, IBM also touches on these concepts: https://www.redbooks.ibm.com/redbooks/pdfs/sg248357.pdf • This talks about more general layering principals, but has a lot of rules of thumb that still apply: https://www.linkedin.com/pulse/build-business-capabilities-apis-nial-darbey • Not directly about these concepts, but Jeff Coble's blog post is somewhat related and a good read: https://medium.com/@jeffcoble/from-product-to-platform-5d6857e55afb • My blog post (Microservices: Building things is easy, building the right thing is hard) also touches briefly on this: https://medium.com/box-tech-blog/microservices-building-things-is- easy-building-the-right-thing-is-hard-b88b6e2474c1 Layered Architecture Articles (continued…) Further Resources