![Investigate Policies
How is our system supposed to react to given events?
Whenever [Event] then [Command]
“We need a lilac between the orange and the blue”
Policy](https://image.slidesharecdn.com/50-171024141229/75/50000-orange-stickies-later-57-2048.jpg?cb=1666085724)
50.000 orange stickies later
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I've spent the last years modelling complex businesses and Software Architectures with EventStorming. The original recipe evolved a lot from the initial one. This is EventStorming state of the art.
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50.000 orange stickies later
- 2. Transactions Redefined A dive into the wormhole with Special KanDDDinsky version
- 3. About me Very hard to explain my job to my mother running www.avanscoperta.it Modelling (almost) everything with sticky notes, markers and a paper roll. Calling this stuff
- 5. 2013 • First Blog Post About EventStorming • One single path from business to aggregate discovery • The beginning of a long journey
- 6. 2017 • Growing Momentum • Many practitioners -> Many Ideas • Many different formats: • Big Picture / Process Modelling / Software Design • Retrospective / Induction / More…
- 7. Big Picture EventStorming Making sense of a huge mess
- 8. Big Picture Workshop Invite the right people -> Business, IT, UX Provide unlimited modelling space Surface, Markers, stickies Model a whole business line with Domain Events
- 9. Establish a timeline Some facilitator tricks will kickstart the discussion quickly
- 10. Explore with domain Events
- 11. The shape of the organization
- 13. Enforcing the timeline Experts will usually post a locally ordered sequence of events But enforcing a shared timeline then triggers long awaited conversations
- 14. Following steps Structure will emerge People and Systems will be displayed … Every layer sparkles a new type of conversation
- 15. Outcome (big Picture): The whole process is visible Massive learning (crossing silo boundaries) consensus around the core problem
- 20. Outcome (big Picture): Multiple storytellings Incremental Notation #NoUML #NoBPMN A language for different tribes #Lean #UX #Agile #SW
- 21. More specifically… No scope limitation (paper roll) Exploration of boundaries (External Systems & People) -> The BOTTLENECK is in the picture. -> The CORE DOMAIN is in the picture
- 23. CLARITY
- 24. The outcome:
- 25. The outcome: A clear business narrative
- 26. The outcome: A clear business narrative A massive blocker
- 27. The outcome: There are recurring patterns in blockers A clear business narrative A massive blocker
- 28. Arrow Voting A clear business narrative A massive blocker
- 29. Arrow Voting A clear business narrative A massive blocker
- 30. Arrow Voting A clear business narrative A massive blocker
- 31. Arrow Voting A clear business narrative A massive blocker
- 32. Arrow Voting A clear business narrative A massive blocker
- 33. Arrow Voting A clear business narrative A massive blocker
- 34. Arrow Voting A clear business narrative A massive blocker
- 35. Arrow Voting A clear business narrative A massive blocker
- 36. Arrow Voting A clear business narrative A massive blocker
- 37. Arrow Voting A clear business narrative A massive blocker
- 38. Arrow Voting A clear business narrative A massive blocker
- 39. Arrow Voting A clear business narrative A massive blocker
- 40. Arrow Voting A clear business narrative A massive blocker
- 41. Arrow Voting You already achieved consensus… A clear business narrative A massive blocker
- 43. Working around the bottleneck • Highest priority -> #No Backlog • Hard to solve -> #NoEstimates • Requires Experiments -> #DDDesign #LeanStartup
- 44. Big Picture In a Startup Invitations are a piece of cake Great attitude No past to compare with :-)
- 45. Big picture in a mature company
- 47. Big picture in a mature company Hard invitation process -> already telling us something Underlying conflicts Corporate Dysfunctions Legacy implementation Dungeon Masters
- 48. Special Tricks?
- 49. Pattern: Incremental Notation After every round the team agrees on the next perspective to investigate Structure, Boundaries, Responsibilities, Systems, Goals, Pitfalls, etc… Every round refines the previous one providing fresher insights
- 50. Pattern: Fuzzy by Design Imprecise definitions… allow everyone to be included in the conversation. Allow Everything to be included in the model Trigger interesting conversation on the spot.
- 51. Process Modelling Making sure we’re doing the right thing
- 52. Scope: Epic or set of features Command Domain Event Domain Event Read Model Domain Event Read Model Preconditions OutcomesThe flow to discover
- 53. What about User stories? A placeholder for future conversation…
- 54. This is a good conversation!
- 55. Colour-puzzle Thinking Policy User User Command Read Model External System Domain Event Command
- 56. Commands / Decisions Command is not yet a software artefact It’s a decision taken by a user (or a piece of software) Outside-in vs Inside-Out thinking Command
- 57. Investigate Policies How is our system supposed to react to given events? Whenever [Event] then [Command] “We need a lilac between the orange and the blue” Policy
- 58. This is where everybody lies
- 59. Ambiguity does not compile
- 60. Policies spectrum IMPLICIT POLICIES: without an explicit agreement EXPLICIT POLICIES: assuming everyone is following them AUTOMATION: Listeners, Sagas, Process managers Policy User Policy
- 62. Challenging value Every step can create or destroy value for given users Discovering multiple currencies Discovering new opportunities Discovering inconsistencies
- 63. Enables cross-perspective conversation Software design, User Experience, Business Modelling, Lean etc.
- 64. I never said it’s easy
- 65. A different job Big picture is for discovery -> Disagreements are OK Here we are reaching an agreement -> Consensus is HARD
- 66. Software design
- 69. The moment someone pronounces the word “aggregate” suddenly everybody from the business have something urgent to do
- 70. Colour-puzzle thinking User Command Read Model External System Domain Event CommandPolicy Aggregate
- 71. Scope: Epic or set of features Command Domain Event Domain Event Read Model Domain Event Read Model Preconditions OutcomesThe flow to discover
- 72. Investigating Aggregates State Machine Logic Focus on BEHAVIOUR, not DATA Postpone NAMING Don’t fall in love with your intuition Aggregate
- 74. Ubiquitous Language(s) SLOWLY introduce consistency
- 75. Ubiquitous Language(s) SLOWLY introduce consistency …I said SLOWLY
- 76. Ubiquitous Language(s) SLOWLY introduce consistency …I said SLOWLY SYMMETRIES are telling you something
- 77. Ubiquitous Language(s) SLOWLY introduce consistency …I said SLOWLY SYMMETRIES are telling you something …but also the lack of them.
- 78. Ubiquitous Language(s) SLOWLY introduce consistency …I said SLOWLY SYMMETRIES are telling you something …but also the lack of them. BRUTE FORCE does not work!
- 79. Ubiquitous Language(s) SLOWLY introduce consistency …I said SLOWLY SYMMETRIES are telling you something …but also the lack of them. BRUTE FORCE does not work!
- 81. Rewriting Events Pedantic Semantic Precision Domain Event
- 82. Rewriting Events Pedantic Semantic Precision … we started from chaos, remember? Domain Event
- 83. Rewriting Events Pedantic Semantic Precision … we started from chaos, remember? Multi-layered -> Emerging Bounded Contexts Domain Event
- 84. Rewriting Events Pedantic Semantic Precision … we started from chaos, remember? Multi-layered -> Emerging Bounded Contexts Key information becomes visible Domain Event
- 85. Rewriting Events Pedantic Semantic Precision … we started from chaos, remember? Multi-layered -> Emerging Bounded Contexts Key information becomes visible Domain Event
- 86. Hard Problems don’t have an Obvious solution
- 87. Discovering Read Models They’re not “Just Data” They’re Decision Making tools Don’t let “reuse” get in the way Read Model
- 88. Discovering Read Models Read Model
- 89. Discovering Read Models 1. Understand the decision Read Model
- 90. Discovering Read Models 1. Understand the decision • Not so easy #DirtyLittleSecrets Read Model
- 91. Discovering Read Models 1. Understand the decision • Not so easy #DirtyLittleSecrets • Rational & Emotional Read Model
- 92. Discovering Read Models 1. Understand the decision • Not so easy #DirtyLittleSecrets • Rational & Emotional 2. Define the necessary data Read Model
- 93. Discovering Read Models 1. Understand the decision • Not so easy #DirtyLittleSecrets • Rational & Emotional 2. Define the necessary data • Data Set Read Model
- 94. Discovering Read Models 1. Understand the decision • Not so easy #DirtyLittleSecrets • Rational & Emotional 2. Define the necessary data • Data Set • Page Layout Read Model
- 95. Discovering Read Models 1. Understand the decision • Not so easy #DirtyLittleSecrets • Rational & Emotional 2. Define the necessary data • Data Set • Page Layout 3. Make it happen Read Model
- 96. Discovering Read Models 1. Understand the decision • Not so easy #DirtyLittleSecrets • Rational & Emotional 2. Define the necessary data • Data Set • Page Layout 3. Make it happen • Projections, Composite UI, Mashups, Good Old Queries, Views and stored procedures. #WhateverItTakes Read Model
- 97. Need Product Owner Badly Exploration is needed in order to challenge the model Product Owner is needed in order to bring reality in KNOWING WITHOUT IMPLEMENTING IS FINE …as long as it’s cheap.
- 98. Design Style Our fuzzy definitions will get progressively rewritten There is no over-design: WE’RE ON THE CORE! Expect a lot of healthy thrashing Bruce Lee state.
- 100. Takeaways
- 102. is my pizza: You can add your toppings
- 103. is my pizza: You can add your toppings With the notable exception of database tables and pineapple
- 104. Domain Events as lingua franca Domain Events are a better choice for… …describing the business …implementing the supporting software
- 105. Events are way better to prevent it
- 106. Events as Published language LOGISTICS Sales OpenedLocal Events are consistent with internal Language TRANSLATION HAPPENS AT THE BORDER, INCLUDING BUSINESS MEANING General purpose events are more independent from local implementation Training Page published PUBLISHING MARKETING Listening Bounded Contexts may subscribe and react accordingly
- 107. They allow ZOOMING!
- 108. From vision to detail (and back) Big Picture Events Hot Spots, Systems, People Conflicts, Goals, Blockers, Boundaries Process Modelling Events + Policies, Commands, Read Models Value Proposition, Policies, Personas, Individual Goals Software Design Events + Aggregates Aggregates, Policies, Read Models, IDs
- 109. From vision to detail (and back) Big Picture Events Hot Spots, Systems, People Conflicts, Goals, Blockers, Boundaries Process Modelling Events + Policies, Commands, Read Models Value Proposition, Policies, Personas, Individual Goals Software Design Events + Aggregates Aggregates, Policies, Read Models, IDs
- 110. From vision to detail (and back) Big Picture Events Hot Spots, Systems, People Conflicts, Goals, Blockers, Boundaries Process Modelling Events + Policies, Commands, Read Models Value Proposition, Policies, Personas, Individual Goals Software Design Events + Aggregates Aggregates, Policies, Read Models, IDs
- 111. A tool for a purpose-driven organization
- 112. Who are we making happy? A tool for a purpose-driven organization
- 113. Questions? Every question is welcome, except “When will you finish the book?”
- 115. References
- 116. References • www.eventstorming.com • EventStormers on Google+ • https://plus.google.com/u/0/communities/113258571348605620818 • LeanPub book in progress: • http://leanpub.com/introducing_eventstorming • Blog: • https://medium.com/@ziobrando • http://ziobrando.blogspot.com • Twitter: @ziobrando • Trainings & Workshop facilitation: • http://www.avanscoperta.it