2020-06-27 DDD Taiwan Community Microservices Bounded Context and everything in Between

This talk is redelivered from DDDDD @vladikk's session by Kim, Kao. The main concept is to figure out how to design microservices with more confidence to make decision. Also mentioned what's the essential concept on API, distributed events, and etc.

Transcript

1. © 2020, Domain Driven Design Taiwan Community Kim Kao, Co-Organizer Domain Driven Design Taiwan Community 27 June, 2020 Microservices Bounded Context And everything in Between @YiKaiKao Kim Kao @Vladikk
2. © 2020, Domain Driven Design Taiwan Community Kim, Kao (高翊凱) • A father of 2 • Love Softball / Baseball • Passionate facilitator • Domain Driven Design Taiwan Community Co-Organizer • Solutions Architect @AWS – Big Serverless Fan !!!
3. © 2020, Domain Driven Design Taiwan Community 95% of the words are spent extolling the benefits of “modularity” and that little, if any, is said about how to achieve it Glenford J. Myers
4. © 2020, Domain Driven Design Taiwan Community Sales & Campain in company
5. © 2020, Domain Driven Design Taiwan Community Product Marketing Strategy Creatives Campaigns Sales Agent Profits Optimization
6. © 2020, Domain Driven Design Taiwan Community Decomposition Strategies Design Heuristics Ubiquitous Language at first ~
7. © 2020, Domain Driven Design Taiwan Community
8. © 2020, Domain Driven Design Taiwan Community Conflicting models Different contexts Dividing the lamguage/model Bounded Context
9. © 2020, Domain Driven Design Taiwan Community Bounded Contexts Marketing Sales Funnel Campaign Placement Landing Page Agency Insertion Order Lead Contact CDR Conversion Desk Campaign Proposition Message Lead
10. © 2020, Domain Driven Design Taiwan Community Decomposition Strategy #1: Bounded Contexts Marketing Service Sales Service
11. © 2020, Domain Driven Design Taiwan Community Marketing Sales Billing Creative Catalog Campaign Management Ads Optimization Identity & Access Contracts Telephony CRM Sales Optimization Commissions Desks Identity & Access
12. © 2020, Domain Driven Design Taiwan Community Business (Sub) Domains
13. © 2020, Domain Driven Design Taiwan Community Business Domain: Customer Acquisition Bounded Context: Marketing Bounded Context: Sales SubDomain: Creative Catalog SubDomain: Campaigns Mgt SubDomain: Ads Optimization SubDomain: Contracts Mgt SubDomain: CRM SubDomain: Sales Optimization SubDomain: Commissions SubDomain: Desk Mgt
14. © 2020, Domain Driven Design Taiwan Community Decomposition Strategy #2: Subdomains Campaign Management service Content Catalog Service Desk Management Service CRM Service Users Service Billing Service
15. © 2020, Domain Driven Design Taiwan Community Marketing Billing Creative Catalog Campaign Management Ads Optimization Identity & Access Contracts Campaign Management Campaign Placement Funnel Banner Website Asset Target Market Landing Page
16. © 2020, Domain Driven Design Taiwan Community Decomposition Strategy #3: Entities Website Asset Target Market Broker Distribution Order
17. © 2020, Domain Driven Design Taiwan Community Quick wrap - Decomposition Strategies Bounded Contexts Subdomains Business Entities and Processes
18. © 2020, Domain Driven Design Taiwan Community Website Funnel Campaign Placement Bounded Contexts? Subdomains? Entities?
19. © 2020, Domain Driven Design Taiwan Community Bounded Contexts == Microservices ?
20. © 2020, Domain Driven Design Taiwan Community LEAD? Campaign Manager Sales Agent 12345… ABCDE…
21. © 2020, Domain Driven Design Taiwan Community Marketing Sales Landing Page Campaign Placement Agency Lead Funnel Contact CDR Conversion Proposition Desk Message Insertion Order Lead
22. © 2020, Domain Driven Design Taiwan Community Marketing Sales Landing Page Campaign Placement Agency Lead Funnel Contact CRM Conversion Proposition Desk Message Insertion Order Lead
23. © 2020, Domain Driven Design Taiwan Community Marketing Support Sales Lead Lead Identity & Access Campaign Mgt Optimization Contracts Desks Telephony Billing Creative Catalog CRM Commissions Optimization
24. © 2020, Domain Driven Design Taiwan Community Bounded Contexts Decomposition #2 Bounded Contexts Decomposition #1 Bounded Contexts Decomposition #3
25. © 2020, Domain Driven Design Taiwan Community Bounded Context Consistency boundary of the language / model Define the biggest valid monoliths Required decomposition boundary
26. © 2020, Domain Driven Design Taiwan Community Choose which context to be microservice ?
27. © 2020, Domain Driven Design Taiwan Community What’s the microservice candidate?
28. © 2020, Domain Driven Design Taiwan Community Service “A service is a unit of functionality exposed to the world” – Juval Lowy “A mechanism to enable access to one or more capabilities, where the access is provided using a prescribed interface” - OASIS
29. © 2020, Domain Driven Design Taiwan Community Service Interface “Any mechanism for getting data in or out of the service” – Randy Shoup
30. © 2020, Domain Driven Design Taiwan Community Service Interface Asynchronous: • Producing events • Consuming events Synchronous: • Request / Response • Bulk ETL
31. © 2020, Domain Driven Design Taiwan Community Service Interface “Any mechanism for getting data in or out of the service” – Randy Shoup
32. © 2020, Domain Driven Design Taiwan Community Service Interface
33. © 2020, Domain Driven Design Taiwan Community A microservice is a service with a micro interface
34. © 2020, Domain Driven Design Taiwan Community Microservice = Microinterface Reducing coupling between services Limits reasons for change Easier to understand Better fault isolation More autonomy between services
35. © 2020, Domain Driven Design Taiwan Community Microservice & Databases Microservices should own its database No external access Access through Microservice’s API only Database = infinite interface!
36. © 2020, Domain Driven Design Taiwan Community 1 Method = Perfect Microservice !!??
37. © 2020, Domain Driven Design Taiwan Community
38. © 2020, Domain Driven Design Taiwan Community
39. © 2020, Domain Driven Design Taiwan Community
40. © 2020, Domain Driven Design Taiwan Community The threshold upon which a system can be decomposed into microservices is defined by the use cases of the system that the microservices are a part of.
41. © 2020, Domain Driven Design Taiwan Community Cost Of Change Monolith Microservices Distributed Monolith
42. © 2020, Domain Driven Design Taiwan Community Cost Of Change Big Ball of Mud Bounded Contexts Distributed Big Ball of Mud Microservices
43. © 2020, Domain Driven Design Taiwan Community Website Funnel Campaign Placement Entities? Subdomains? Microservice candidate - dependens Resolve Global Complexity
44. © 2020, Domain Driven Design Taiwan Community “Global complexity … the complexity of the overall structure of a program or system. i.e, the degree of association or interdependence Among the major pieces of a program” Glenford J. Myers - 1978 Composite / Structured Design
45. © 2020, Domain Driven Design Taiwan Community When you design a system…, then if the features can be break into … loosely bound groups of relatively closely bound features, then that division is a good thing to be mad a part of the design. This is just good engineering. Tim Berners-Lee Principles of design, 1998
46. © 2020, Domain Driven Design Taiwan Community Services + Good Engineering = Microservices
47. © 2020, Domain Driven Design Taiwan Community Its is not only necessary to make sure your own system is designed to be made of modular parts. It is also necessary to realize that your own system… should always be designed to be a part of another larger system. Tim Berners-Lee Principles of design, 1998
48. © 2020, Domain Driven Design Taiwan Community A major part of this paper will be concerned with the question of how good modularity can be achieved, that is, how modules can be chosen to as to minimize the connections between them. Barbara Liskov A design methodology for reliable software systems, 1972
49. © 2020, Domain Driven Design Taiwan Community A microservice is a service with a micro interface. The threshold upon which a system can be decomposed Into microservices is defined by the use cases of the System that the microservices are a part of.
50. © 2020, Domain Driven Design Taiwan Community Design Heuristics
51. © 2020, Domain Driven Design Taiwan Community Heuristic #1: Decompose to Bounded Contexts Do not implement conflicting models in the same service. Always decompose to Bounded Contexts.
52. © 2020, Domain Driven Design Taiwan Community Heuristic #2: Don’t First Law of Distributed Object Design: “Don’t distribute your objects” Martin Fowler
53. © 2020, Domain Driven Design Taiwan Community Heuristic #2: Don’t Benefits Additional Complexity
54. © 2020, Domain Driven Design Taiwan Community
55. © 2020, Domain Driven Design Taiwan Community DDD - Subdomains Core Supporting Generic
56. © 2020, Domain Driven Design Taiwan Community Generic Subdomains No competitive advantage Everybody is implementing in the same way Complex business logic Services : Billing, A&A, Telepony …
57. © 2020, Domain Driven Design Taiwan Community Heuristic #3: Buy/Adopt Generic subdomains 3rd party product Your system Anti-Corruption Layer
58. © 2020, Domain Driven Design Taiwan Community Core Subdomains Inventing something new Optimizing existing practices Competitive advantage Complex business logic Change often Services : Campaign, Ad Optimization, CRM, Sales, Commissions
59. © 2020, Domain Driven Design Taiwan Community Heuristic #4: Core Subdomains – Don’t Rush Adhere to subdomain’s boundaries. Decompose further only when you acquire domain knowledge.
60. © 2020, Domain Driven Design Taiwan Community Supporting Subdomains No competitive advantage Support the Core Subdomains Can’t be bought / adopted Simple bussiness logic Services : Creative Catalog, Contracts, Desks
61. © 2020, Domain Driven Design Taiwan Community Heuristic #5: Supporting Subdomains - Safe Safe to decompose beyond the subdomain’s boundaries.
62. © 2020, Domain Driven Design Taiwan Community Heuristic #6: Evaluate Consistency Requirements Method A Method B
63. © 2020, Domain Driven Design Taiwan Community Heuristic #6: Evaluate Consistency Requirements Method A Method B Conscurrency control? – Same service Service A
64. © 2020, Domain Driven Design Taiwan Community Heuristic #6: Evaluate Consistency Requirements Conscurrency control? – Same service Method A Service A Method B Service B Sync Call
65. © 2020, Domain Driven Design Taiwan Community Heuristic #6: Evaluate Consistency Requirements Eventual Consistency? – Two Services, async communication Method A Service A Method B Service B Async communication
66. © 2020, Domain Driven Design Taiwan Community Heuristic #6: Evaluate Consistency Requirements Concurrency control? – Same Service Read last write? – Two services, sync communication Eventual consistency? – Two services, async communication
67. © 2020, Domain Driven Design Taiwan Community Heuristic #7: Public / Private Events … … … … … … Event Type 3 Event Type 2 Event Type 1 Event Type 100 …
68. © 2020, Domain Driven Design Taiwan Community Heuristic #7: Public / Private Events Service emailChanged phoneNumberChanged addressChanged contactDetailChanged Private event types (Implementation details) public event types (public interface)
69. © 2020, Domain Driven Design Taiwan Community Heuristic #7: Public / Private Events Events? Domain Events State Change Events Private Public
70. © 2020, Domain Driven Design Taiwan Community Heuristic #8: Make Events Explicit Service AgentAssignedToLead AgentAssignedToLead AgentAssignedToLead
71. © 2020, Domain Driven Design Taiwan Community Heuristic #8: Make Events Explicit Service AgentAssignedToLead AgentAssignedToLead AgentUnassignedToLead
72. © 2020, Domain Driven Design Taiwan Community Heuristic #9: Evaluate reasons for Change Method A Service A Method B Service B Sync Call
73. © 2020, Domain Driven Design Taiwan Community Heuristic #9: Evaluate reasons for Change Same reasons for change? Same rate of change? Can be decoupled? Should be the same service?
74. © 2020, Domain Driven Design Taiwan Community Heuristic #10: Evaluate Services’ “Doors”
75. © 2020, Domain Driven Design Taiwan Community Wrap it up • A service is a unit of functionality exposed to the world through its public interface • A microservice is a service with micro interface • The “Micro-interface” is relative to the use cases of the system that the service is a part of
76. © 2020, Domain Driven Design Taiwan Community Wrap it up • Heuristic #1: Always decompose to Bounded Contexts • Heuristis #2: Don’t go further, unless you have to • Heuristic #3: Buy/Adopt generic subdomains • Heuristic #4: Core subdomains – don’t rush • Heuristic #5: Supporting subdomains can be decomposed ear • Heuristic #6: Evaluate Consistency Requirements • Heuristic #7: Private / Public Events • Heuristic #8: Explicit Define Events • Heuristic #9: Evaluate Reasons for Change • Heuristic #10: Evaluate Services’ “Doors”
77. © 2020, Domain Driven Design Taiwan Community Cost Of Change Big Ball of Mud Bounded Contexts Distributed Big Ball of Mud Microservices
78. © 2020, Domain Driven Design Taiwan Community Reference from Vladikk
79. © 2020, Domain Driven Design Taiwan Community Thank You!
80. © 2020, Domain Driven Design Taiwan Community Q&A