Event Storming to Solution Space

Transcript

1. Event Storming to Solution Space Painting by Vassily Kandinsky
2. Better By Design – Excel By Build • Software Engineer/Architect • M.S., MBA CU Boulder • www.linkedin.com/in/rshagisultanov • rshagisultanov@gmail.com • @RinatSh • DDD, system architecture, devops, agile, team orgs, startup • Principal Credits: Nick Tune, Paul Rayner, Alberto Brandolini
3. Why This Talk? Model Solution Business
4. Agenda l Quick overview of Domain-Driven Design l Event Storming l Domain Storytelling l User Story Mapping
5. Why Complex business rules and processes Knowledge silos Numerous diverse and complex interactions with human users and systems
6. How Do We Learn Fast together? Use Cases ERD Sequence Diagrams Activity Diagram User Story Mapping Customer Journey Service Blueprint ...
12. What we need? Shared and collaborative learning Learn not the entities, but about the behavior (add time scale) Visual map of flow of events
13. THE CRITICAL COMPLEXITY OF MOST SOFTWARE PROJECTS IS IN UNDERSTANDING THE DOMAIN ITSELF Eric Evans
14. Tactical DDD (Something Familiar) Code structures and patterns
15. Strategic DDD (Important for Learning) Modelling and decomposition
17. Hexagonal Architecture Plays well with tactical DDD
18. What is Strategic DDD? Shared model of understanding Discovering the most important parts of the problem space Transform the problem space into a useful solution space
19. Domain Moving Optimization Trucking ERP Truck Location Order Dispatch Terminal Routing Decomposition of Domain into sub-domains
20. Classifying Sub-domains ü Core ü Supporting ü Generic Moving Optimization Trucking ERP Truck Location Order Dispatch Terminal Routing
21. Domains
22. Bounded Context Trucking ERP Truck Location Order Moving Optimization Dispatch Use Business Capability or Sub-domain as starting point Routing
23. Bounded Context & Ubiquitous Language Driver Leg Order Moving Optimization Dispatch Order Order Plan Job Driver Plan
24. Context Map Dispatch Moving Communication between all bounded contexts U D
25. Relationship Types ü Shared Kernel ü Domain logic - not cross-cutting concerns ü Customer - Supplier ü Conformist ü Open Host Service ü Separate Ways ü Anti-Corruption Layer
26. Uncovering Domain Models
27. “Software development is a learning process Working code is a side effect” Alberto Brandolini
28. Event Storming
29. Place events on a timeline (orange stickies)
30. Types of Domain Events Something that happened in the business that your domain experts care about
31. Questions/Clarifications Needed (Pink Stickies) • Question • Risks/Warnings • Assumptions • Consideration Points • !!! Postpone the answer • !!! Discuss only what is visible
33. DEVELOPMENT TEAM MEMBERS AND BUSINESS PEOPLE GATHER IN A ROOM AND TOGETHER WE CREATE A VISUAL MAP OF THE FLOW OF EVENTS
39. Sourced from leanpub.com/introducing_eventstorming
41. Sample Execution Create visual annotations Storm domain events and place them on the time order Note and place the issues and questions in purple Group the events/issues together and vote for the hotspots Identify the business processes in lilac note and draw arrow from event to process Note commands which cause events on light blue sticky Identify aggregates/entities changed by command on a yellow sticky Place a role/user on the small yellow sticky with the stick figure Place the policies when the flow requires decision making. Use purple sticky Draw bounded contexts and domains (clusters) Identify the views/read models required for commands to run. Use green stickies
42. Event Storming
44. How-To: Event Storming (I) NO CHAIRS MODELING SPACE (WALL) IS 24 FT OR MORE HAVE ENOUGH STICKIES, MARKERS AND MASKING TAPE POST FIRST – DISCUSS LATER ESTABLISH A TIMEBOX FOR THE SESSION: 2-3 HOURS + FOLLOW- UPS HAVE ENOUGH FOOD AND DRINKS MITIGATE ADMINISTRATIVE HIERARCHY
45. How-To: Event Storming (II) Focus On Learning and Understanding Focus On Use clarifying questions: •What circumstances would cause this to happen? •What is the path to get here? •What is a good example? •What is the term meaning? •What might we need to do or to achieve? •What else might happen? Use Start with CONCRETE business example Start Clarify fuzzy concepts (NO to CRUD, use real verbs) Clarify
46. How-To: Event Storming (III) When NOT to use ES: ▪ Simple CRUD ▪ Distributed Team ▪ Large group/hierarchical group
47. Why Event Storming? • Cultivate mutual shared understanding • Uncover misunderstandings & missing concepts • Avoid rework Collaborative learning • Visual, tactile representation of system behaviour & outcomes • Smoother transition to a rich domain model, design and coding Model & explore complex domains Business Model to Code Fast
48. Additional Modeling Techniques • Business Model Canvas • Domain Storytelling (Stefan Hofer and Henning Schwentner) • User Story Mapping (Jeff Patton) • Temporal/Event Modeling (Adam Dymitruk)
49. Business Model Canvas ▪ Identify the core sub-domains ▪ Focus on important aspects of business and software system
50. Domain Storytelling • Actors: a person, a customer, or a more technical thing like a car or a ship • Work objects: a document or a message, or more abstract things such as a route for a transport. • Arrows for activities • Numbered and story based https://domainstorytelling.org/
51. User Story Mapping • Focus on: Users. Flow, Backbone, Tasks • Narratives and story telling • Look at system as a whole • Project into releases as cohesive end to end stories • Ref: Jeff Patton
52. Solutions as Code Patterns and Libraries
53. Tactical DDD (Something Familiar) Code structures and patterns
54. CQRS & Event Sourcing Event Store Client Command Query Domain Event
55. CQRS & Event Sourcing l Command l Request (e.g. CreateUser) l Domain Event l Verb in past tense (e.g. UserCreated) l Event Store l Projections, Snapshotting & Versioning l Replay of events & Log for free l CQRS + ES or CQRS alone
56. Libraries and Reference Architectures • https://axoniq.io/ (Allard Buijze) • https://kalele.io/platform/ (vlingo, Vaughn Vernon) • https://aspnetboilerplate.com/ • Surprise: Reference architecture from Microsoft eShopOnContainers
57. Summary ü Strategic DDD ü Focus on Core sub-domains ü Decomposition into Bounded Contexts ü Ubiquitous Language ü Modelling Techniques ü Event Storming ü Domain Storytelling ü User Story Mapping
58. Resources • Virtual DDD Meetup (1-2 times/month via Zoom) • Find DDD Meetup locally (DDD Denver) • ExploreDDD/DDDEurope on YouTube • https://medium.com/nick-tune-tech-strategy- blog