Vertical Slices in .NET - Bojan Veljanovski, March 2016, MK.NET UG
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The document discusses user intent in software development and introduces the CQRS (Command Query Responsibility Segregation) pattern, which separates writing and reading data into distinct classes. It contrasts horizontal and vertical user stories and slices, advocating for vertical slices that focus on features rather than technical layers to enable better organization and understanding of code. The document highlights the benefits of vertical slicing, such as clearer responsibility, isolation of complexity, and the potential for incremental feature releases.
Vertical Slices in .NET - Bojan Veljanovski, March 2016, MK.NET UG
- 1. Vertical Slices in .NET Bojan Veljanovski, CTO at HASELT 1
- 2. What is an user’s intent in software? 2
- 3. User Intent - Reads and Writes - WRITE is a request modeled as COMMAND triggered via HTTP POST - READ is a request modeled as QUERY triggered via HTTP GET - Commands modify data - Queries retrieve data 3
- 4. User Intent - CQRS CQRS is a simple pattern, writing and reading data is placed in 2 separate classes which have single responsibility. 4
- 5. DISCLAIMER Nope… there is no silver bullet. 5
- 6. What we are going to talk about - Overview - Horizontal vs. Vertical user stories - Horizontal vs. Vertical slices - Commands & Queries - Feature folders - DEMO code - Summary 6
- 7. “Two“ starting points to build a system - Horizontal first - Vertical first 7
- 8. Horizontal vs. Vertical user stories - Horizontal - Story 1: Create the new DB Table for Users - Story 2: Create the DAL to access the DB Users - Story 3: Create the Users business layer code that references the DAL - Story 4: Write the Users UI screen - Vertical - Story 1: User can register and provide username and password. - Story 2: User can manage multiple addresses. - Story 3: User can add additional contact fields (phone, email, etc). - Story 4: User can subscribe to a subscription plan. 8
- 9. Horizontal vs. Vertical user stories - Horizontal - Implement the database layer for A, B and C - Implement the business logic layer for A, B and C - Implement the user interface for A, B and C - Vertical - Implement A from end to end - Implement B from end to end - Implement C from end to end 9
- 10. Horizontal slicing is not natural in agile - Changes usually happen vertically - You limit your application to the same horizontal constraints for all features (regardless of the size and complexity) - ...and more 10
- 11. “Slicing” is a team organization thing too! 11
- 12. Vertical Slices over Horizontal Slices - Horizontal slices is organization by technical layers. - Vertical slices is organization by features (business requirements). 12
- 13. Vertical Slicing: The Stakeholder Stakeholders talk and eat the cake in vertical slices. They want one delicious piece at a time, not only the vanila part. Why don't we structure our code vertically as well? 13
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- 21. Addressing cross-cutting concerns - Loggers - Validators - Transactions 21
- 22. ASP.NET MVC - Feature Folders ViewEngine 22
- 23. ASP.NET MVC - Feature Folders ViewEngine 23
- 25. Can it easily evolve to CQRS? 25
- 26. Can it easily evolve to SOA/Microservices? 26
- 27. SUMMARY: Characteristics of good Vertical Slices - Code is structured primarily by feature, secondary by layer - Have single responsibility (business-oriented) - Encapsulated and decoupled from other slices - Complexity and defects are isolated in each slice, instead of each layer - Increases developer’s understanding of each feature as a whole - Enables incremental releases of features - Enables faster feedback loop 27
- 28. SUMMARY: Trade-offs and Challenges - Complete mindset shift - Developers must be all-round-shaped (back, front, middle, db, all) - Now you have twice as many classes as before 28