Microservices, Boounded Contexts, and Everything in Between

Microservices, Boounded Contexts, and Everything in Between

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Vladik Khononov

September 10, 2020
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  1. vladikk doit-intl.com MICROSERVICES BOUNDED CONTEXTS AND EVERYTHING IN BETWEEN

  2. vladikk doit-intl.com ”95% of the words are spent extolling the

    benefits of “modularity” and that little, if anything, is said about how to achieve it” Glenford J. Myers
  3. vladikk doit-intl.com

  4. vladikk doit-intl.com “MICROSERVICES FTW!!!!!!!!1” Me @ Internovus

  5. vladikk doit-intl.com “MICROSERVICES FTW!!!!!!!!1” Me @ Internovus

  6. vladikk doit-intl.com ”95% of the words are spent extolling the

    benefits of “modularity” and that little, if anything, is said about how to achieve it” Glenford J. Myers
  7. vladikk doit-intl.com

  8. vladikk doit-intl.com

  9. vladikk doit-intl.com Decomposi)on Strategies Microservices Design Heuris)cs

  10. vladikk doit-intl.com Decomposi)on Strategies Microservices Design Heuris)cs

  11. vladikk doit-intl.com Decomposi)on Strategies Microservices Design Heuris)cs

  12. vladikk doit-intl.com INTERNOVUS 01 BUSINESS DOMAIN

  13. vladikk doit-intl.com Your Product Marketing Strategy Creatives Campaigns Sales Agents

    Optimization Profits
  14. vladikk doit-intl.com DECOMPOSITION 02 STRATEGIES

  15. vladikk doit-intl.com Bounded Contexts

  16. vladikk doit-intl.com

  17. vladikk doit-intl.com Domain Expert Software Developer

  18. vladikk doit-intl.com Business Domain Expert Software Developer ??? !!! Ubiquitous

    Language
  19. vladikk doit-intl.com Campaigns Sales Agents Your Product Marketing Strategy Creatives

    Optimization Profits
  20. vladikk doit-intl.com Sales Agent Campaign Manager ??? !!! LEAD?

  21. vladikk doit-intl.com Conflicting models Different contexts Dividing the language/model Bounded

    Context
  22. vladikk doit-intl.com MarkeCng Sales Lead Lead Funnel Campaign Placement Landing

    Page Agency Insertion Order Message Campaign Proposition Desk Conversion Contact CDR Bounded Contexts
  23. vladikk doit-intl.com MarkeCng Service Sales Service DecomposiCon Strategy #1: Bounded

    Contexts
  24. vladikk doit-intl.com MarkeCng Sales Commissions Desks Sales Optimization CRM Telephony

    Creative Catalog Contracts Billing Campaign Management Identity & Access Ads Optimization Identity & Access
  25. vladikk doit-intl.com Business (Sub)Domains

  26. vladikk doit-intl.com Business Domain: Customer Acquisi)on Bounded Context: Marke)ng Bounded

    Context: Sales Subdomain: Crea)ve Catalog Subdomain: Campaigns Mngmt Subdomain: Ads Op)miza)on Subdomain: Contracts Mngmt Subdomain: CRM Subdomain: Sales Op)miza)on Subdomain: Commissions Subdomain: Desks Mngmt
  27. vladikk doit-intl.com DecomposiCon Strategy #2: Subomains Campaign Management Service Content

    Catalog Service Desks Management Service CRM Service Users Service Billing Service
  28. vladikk doit-intl.com Business EnCCes and Processes

  29. vladikk doit-intl.com MarkeCng Creative Catalog Contracts Billing Campaign Management Identity

    & Access Optimization Campaign Management Campaign Placement Funnel Banner Landing Page Website Zone Asset Publisher Target Market
  30. vladikk doit-intl.com DecomposiCon Strategy #3: EnCCes Website Asset Target Market

    Broker Distribu)on Customer
  31. vladikk doit-intl.com DecomposiCon Strategies Bounded Contexts Subdomains Business Entities and

    Processes
  32. vladikk doit-intl.com SHOW ME THE MICROSERVICES!

  33. vladikk doit-intl.com MarkeCng Creative Catalog Contracts Billing Campaign Management Identity

    & Access Optimization Campaign Management Campaign Placement Funnel Banner Landing Page Website Zone Asset Publisher Target Market Campaign Website Placement Funnel Bounded Contexts? Subdomains? EnCCes?
  34. vladikk doit-intl.com Bounded Contexts == Microservices ?

  35. vladikk doit-intl.com Sales Agent Campaign Manager ??? !!! LEAD?

  36. vladikk doit-intl.com MarkeCng Sales Lead Lead Funnel Campaign Placement Landing

    Page Agency Insertion Order Message Campaign Proposition Desk Conversion Contact CDR
  37. vladikk doit-intl.com MarkeCng Sales Commissions Desks Optimization CRM Telephony Creative

    Catalog Contracts Billing Campaign Management Identity & Access Optimization Identity & Access Lead Lead
  38. vladikk doit-intl.com MarkeCng Creative Catalog Campaign Management Optimization Lead Sales

    Commissions Optimization CRM Lead Desks Telephony Support Contracts Billing Identity & Access
  39. vladikk doit-intl.com Bounded Contexts Decomposi)on #1 Bounded Contexts Decomposi)on #2

    Bounded Contexts Decomposi)on #3
  40. vladikk doit-intl.com Bounded Context Consistency boundary of the language /

    model Define the biggest valid monoliths Required decomposition boundary
  41. vladikk doit-intl.com Bounded Contexts == Microservices? No

  42. vladikk doit-intl.com Campaign Management Campaign Placement Funnel Banner Landing Page

    Website Zone Asset Publisher Target Market Campaign Website Placement Funnel MarkeCng Creative Catalog Contracts Billing Campaign Management Identity & Access Optimization Bounded Contexts? No Subdomains? EnCCes?
  43. vladikk doit-intl.com MICROSERVICES 03

  44. vladikk doit-intl.com “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 Service
  45. vladikk doit-intl.com Service Interface “Any mechanism for getting data in

    or out of the service” - Randy Shoup
  46. vladikk doit-intl.com Service Interface Asynchronous: • Producing events • Consuming

    events Synchronous: • Request / Response • Bulk ETL
  47. vladikk doit-intl.com Service Interface “Any mechanism for getting data in

    or out of the service” - Randy Shoup
  48. vladikk doit-intl.com Service Interface

  49. vladikk doit-intl.com Services ➜ Microservice

  50. vladikk doit-intl.com A microservice is a service with a micro

    interface
  51. vladikk doit-intl.com Microservice = Microinterface Reducing coupling between services Limits

    reasons for change Easier to understand Better fault isolation More autonomy between services
  52. vladikk doit-intl.com Microservice = Microinterface Reducing coupling between services Limits

    reasons for change Easier to understand Better fault isolation More autonomy between services
  53. vladikk doit-intl.com Microservice & Databases Microservices should own its database

    No external access Access through Microservice’s API only Database = infinite interface!
  54. vladikk doit-intl.com 1 Method = Perfect Microservice !!??

  55. vladikk doit-intl.com

  56. vladikk doit-intl.com

  57. vladikk doit-intl.com

  58. vladikk doit-intl.com

  59. vladikk doit-intl.com STAFF ONLY STAFF ONLY

  60. vladikk doit-intl.com 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.
  61. vladikk doit-intl.com Monolith Microservices Distributed Monolith Cost of Change

  62. vladikk doit-intl.com Big Ball Of Mud Bounded Contexts Microservices Distributed

    Big Ball Of Mud Avg. Service Size
  63. vladikk doit-intl.com Campaign Management Campaign Placement Funnel Banner Landing Page

    Website Zone Asset Publisher Target Market Campaign Website Placement Funnel Subdomains? EnCCes?
  64. vladikk doit-intl.com

  65. vladikk doit-intl.com ”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
  66. vladikk doit-intl.com ”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 Composite / Structured Design, 1978
  67. vladikk doit-intl.com When you design a system…, then if the

    features can be broken into … loosely bound groups of rela>vely closely bound features, then that division is a good thing to be made a part of the design. This is just good engineering. Tim Berners-Lee Principles of design, 1998
  68. vladikk doit-intl.com Services + Good Engineering = Microservices

  69. vladikk doit-intl.com 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
  70. vladikk doit-intl.com A major part of this paper will be

    concerned with the ques>on of how good modularity can be achieved, that is, how modules can be chosen so as to minimize the connec5ons between them. Barbara Liskov A design methodology for reliable soIware systems, 1972
  71. vladikk doit-intl.com 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.
  72. vladikk doit-intl.com A microservice is a service with a micro

    interface. The threshold upon which the system can be decomposed is defined by the use cases of the system that the microservices are a part of. …how to evaluate?
  73. vladikk doit-intl.com DESIGN 04 HEURISTICS

  74. vladikk doit-intl.com HeurisCc #1: Decompose to Bounded Contexts Do not

    implement conflicting models in the same service. Always decompose to Bounded Contexts.
  75. vladikk doit-intl.com HeurisCc #2: Don’t First Law of Distributed Object

    Design: “Don’t distribute your objects” MarCn Fowler
  76. vladikk doit-intl.com HeurisCc #2: Don’t Benefits Addi)onal Complexity

  77. vladikk doit-intl.com MONOLITH SYSTEM DESIGN THAT UNDERMINES DELIVERY OF FUNCTIONAL

    OR NON-FUNCTIONAL REQUIREMENTS
  78. vladikk doit-intl.com HeurisCc #2: Don’t Benefits Addi)onal Complexity

  79. vladikk doit-intl.com HeurisCc #2: Don’t Benefits Addi)onal Complexity

  80. vladikk doit-intl.com Core Supporting Generic

  81. vladikk doit-intl.com Generic Subdomains No competitive advantage Everybody is implementing

    in the same way Complex business logic
  82. vladikk doit-intl.com MarkeCng Sales Commissions Desks Optimization CRM Telephony Creative

    Catalog Contracts Billing Campaign Management Identity & Access Optimization Identity & Access Generic
  83. vladikk doit-intl.com HeurisCc #3: Buy/Adopt Generic Subdomains Your System 3rd

    party product
  84. vladikk doit-intl.com HeurisCc #3: Buy/Adopt Generic Subdomains Your System 3rd

    party product An)-Corrup)on Layer
  85. vladikk doit-intl.com Core Subdomains Inventing something new Optimizing existing paractices

    Competitive advantage Complex business logic Change often
  86. vladikk doit-intl.com MarkeCng Sales Commissions Desks Sales Optimization CRM Telephony

    Creative Catalog Contracts Billing Campaign Management Identity & Access Ad Optimization Identity & Access Generic Core
  87. vladikk doit-intl.com Core Subdomains Inventing something new Optimizing existing paractices

    Competitive advantage Complex business logic Change often
  88. vladikk doit-intl.com HeurisCc #4: Core Subdomains - Don’t Rush Adhere

    to subdomain’s boundaries. Decompose further only when you acquire domain knowledge.
  89. vladikk doit-intl.com SupporCng Subdomains No competitive advantage Support the Core

    Subdomains Can’t be bought / adopted Simple business logic
  90. vladikk doit-intl.com MarkeCng Sales Commissions Desks Sales Optimization CRM Telephony

    Creative Catalog Contracts Billing Campaign Management Identity & Access Ad Optimization Identity & Access Generic Core Supporting
  91. vladikk doit-intl.com SupporCng Subdomains No competitive advantage Support the Core

    Subdomains Can’t be bought / adopted Simple business logic
  92. vladikk doit-intl.com HeurisCc #5: SupporCng Subdomains - Safe Safe to

    decompose beyond the subdomain’s boundaries.
  93. vladikk doit-intl.com Core Supporting Generic

  94. vladikk doit-intl.com HeurisCc #6: Evaluate Consistency Requirements Method A Method

    B
  95. vladikk doit-intl.com HeurisCc #6: Evaluate Consistency Requirements Concurrency control? -

    Same service Method A Method B Service A
  96. vladikk doit-intl.com HeurisCc #6: Evaluate Consistency Requirements Read last write?

    - Two services, synchronous communication Service A Method A Service B Method B Sync call
  97. vladikk doit-intl.com HeurisCc #6: Evaluate Consistency Requirements Eventual consistency? -

    Two services, asynchronous communication Service A Method A Service B Method B Asynchronous Communication
  98. vladikk doit-intl.com HeurisCc #6: Evaluate Consistency Requirements Concurrency control? -

    Same service Read last write? - Two services, sync communication Eventual consistency? - Two services, async communication
  99. vladikk doit-intl.com Service A Method A Service B Method B

    Asynchronous Communication
  100. vladikk doit-intl.com HeurisCc #7: Public / Private Events Service Event

    Type 1 Event Type 2 Event Type 3 Event Type 4 Event Type 5 Event Type 6 Event Type 1000 …
  101. vladikk doit-intl.com HeurisCc #7: Public / Private Events Service Event

    Type 1 Event Type 2 Event Type 3 Event Type 4 Event Type 5 Event Type 6 Private event types (Implementation details) } Event Type 1000 …
  102. vladikk doit-intl.com HeurisCc #7: Public / Private Events Service Event

    Type 1 Event Type 2 Event Type 3 Event Type 4 Event Type 5 Event Type 6 Event Type 1000 … Private event types (Implementation details) }Public event types (Public interface) }
  103. vladikk doit-intl.com Service EmailChanged PhoneNumberChanged AddressChanged ContactDetailsChanged HeurisCc #7: Public

    / Private Events
  104. vladikk doit-intl.com Service EmailChanged PhoneNumberChanged AddressChanged ContactDetailsChanged Private event types

    (Implementation details) } Public event type (Public interface) } HeurisCc #7: Public / Private Events
  105. vladikk doit-intl.com HeurisCc #7: Public / Private Events Events? Domain

    Events State Change Events
  106. vladikk doit-intl.com HeurisCc #7: Public / Private Events Events? Domain

    Events State Change Events Private Public
  107. vladikk doit-intl.com HeurisCc #8: Make Events Explicit Eliminate ambiguity

  108. vladikk doit-intl.com HeurisCc #8: Make Events Explicit Service AgentAssignedToLead AgentAssignedToLead

    AgentAssignedToLead
  109. vladikk doit-intl.com HeurisCc #8: Make Events Explicit Service AgentAssignedToLead AgentUnassignedToLead

    AgentAssignedToLead
  110. vladikk doit-intl.com HeurisCc #9: Evaluate Reasons for Change Service A

    Service B
  111. vladikk doit-intl.com Same reasons for change? Same rate of change?

    Can be decoupled? Should be the same service? HeurisCc #9: Evaluate Reasons for Change
  112. vladikk doit-intl.com

  113. vladikk doit-intl.com HeurisCc #10: Evaluate Services’ “Doors”

  114. vladikk doit-intl.com HeurisCc #10: Evaluate Services’ “Doors” STAFF ONLY STAFF

    ONLY
  115. vladikk doit-intl.com WRAP UP 05

  116. vladikk doit-intl.com 1. A service is a unit of func)onality

    exposed to the world through its public interface. 2. A microservice is a service with micro interface 3. The “micro-interface” is rela)ve to the use cases of the system that the service is a part of
  117. vladikk doit-intl.com Heuris)c #1: Always decompose to Bounded Contexts Heuris)c

    #2: Don’t go further, unless you have to Heuris)c #3: Buy/adopt generic subdomains Heuris)c #4: Core subdomains - don’t rush Heuris)c #5: Suppor)ng subdomains can be decomposed early
  118. vladikk doit-intl.com Heuris)c #6: Evaluate Consistency Requirements Heuris)c #7: Private

    / Public Events Heuris)c #8: Explicitly Define Events Heuris)c #9: Evaluate Reasons for Change Heuris)c #10: Evaluate Services’ “Doors”
  119. vladikk doit-intl.com Big Ball Of Mud Bounded Contexts Microservices Distributed

    Big Ball Of Mud Avg. Service Size
  120. vladikk doit-intl.com Bibliography 1. A Design Methodology for Reliable Soeware

    Systems, Barbara Liskov 2. Designing Autonomous Teams and Services, Nick Tune & Scoh Millet 3. Composite/Structured Design, Glenford Myers 4. Domain-Driven Design: Tackling Complexity in the Heart of Soeware, Eric Evans 5. Emerging Boundaries, Mathias Veraes 6. Implemen)ng Domain-Driven Design, Vaughn Vernon 7. Enterprise Integra)on Paherns, Gregory Hohpe, at al 8. Long Sad Story of Microservices, Greg Young 9. Managing Data in Microservices, Randy Shoup 10. Microservices, At Last Some Boundaries, Eric Evans 11. On the Criteria to be Used in Decomposing Systems Into Modules, David Parnas 12. Paherns of Enterprise Applica)on Architecture, Mar)n Fowler, at al 13. Principles of Design, Tim Berners-Lee 14. Programming WCF Services, Juval Lowy 15. What Every Programmer Should Know About Object Oriented Design, Melir Page-Jones
  121. https://bit.ly/2ptJ5fS THANK YOU! @vladikk vladikk.com https://bit.ly/31nSD9c http://careers.doit-intl.com

  122. QUESTIONS? @vladikk vladikk.com