Presentation at Coolblue Behind the Scenes on using Ports and Adapters to achieve an architecture that is independent of frameworks and infrastructure

1. Framework Independent
Architectures.
Nathan Johnstone – n.johnstone@coolblue.nl

2. Focus

5. A Bit About Me

6. Early Software Development

8. Pigs != Pegs

9. The Starting Point

10. Joining a Team

11. Infrastructure Dependencies
Web API
Message
Service
Scheduler

12. Application Assemblies
Web API
Message
Service
Scheduler
Data
Access
Domain Common

13. Application Dependencies
Web API
Message
Service
Scheduler
Data
Access
Domain Common

14. Class Library Dependencies
Web API
Message
Service
Scheduler
Data
Access
Domain Common

15. N-Tier
Web API
Data
Access
Domain

16. Isn't Something Missing?

17. Pain

18. Leakage

19. DRY - Reuse Reuse Reuse !

20. Test Coverage
Unit Tests
Component Tests
Acceptance
Tests
Integration Tests

21. Implementing Integration Tests

22. Interfaces Colocated With Implementations
Data Access Domain
PurchaseOrderSubmitServiceIPurchaseOrderRetriever
PurchaseOrderRetriever
?

23. Who Owns The Interface ?

24. Colocation Problems
Data Access Domain
PurchaseOrderSubmitServiceIPurchaseOrderRetriever
PurchaseOrderPurchaseOrderDocument

25. Isolation Violation
PurchaseOrderDocument
Domain

26. Reference Direction vs Control Direction
Presentation
Layer
Data Access
Layer
Business Logic
Layer
Reference DirectionControl Direction

27. Ports & Adapters Introduction
Allow an application to equally be driven by users, programs, automated test
or batch scripts, and to be developed and tested in isolation from its eventual
run-time devices and databases.

28. Hexagonal Architecture

29. Inside / Outside

30. First Port - Persistence
Web API
Message
Service
Scheduler
Data
Access
Domain Common
Persistence
Adapter

31. Second Port - Commands
Web API
Message
Service
Scheduler
Data
Access
Domain
Persistence
Adapter
Command
Adapter

32. Upstream / Downstream Ports

33. Third Port - Notification
Web API
Message
Service
Scheduler
Data
Access
Domain
Persistence
Adapter
Command
Adapter
Notification
Adapter

34. Clean Up
Web API
Message
Service
Scheduler
Data
Access
Domain
Persistence
Adapter
Command
Adapter
Notification
Adapter

35. Domain
Hexagonal - Domain
Web API
Message
Service
Scheduler
Persistence
Adapter
Command
Adapter
Notification
Adapter

36. Domain
Hexagonal - Persistence Port
Web API
Message
Service
Scheduler
Persistence
Adapter
Command
Adapter
Notification
Adapter

37. Domain
Hexagonal - Command Port
Web API
Message
Service
Scheduler
Persistence
Adapter
Command
Adapter
Notification
Adapter

38. Domain
Hexagonal - Notification Port
Web API
Message
Service
Scheduler
Persistence
Adapter
Command
Adapter
Notification
Adapter

39. Hosts Are Types of Adapters
Web Service
Test Harness
Command
Line
Daemon
Windows
Service
Graphical UI

40. Domain
Hexagonal - Host Port
Web API
Message
Service
Scheduler
Persistence
Adapter
Command
Adapter
Notification
Adapter
Host Port

41. Advantages - Domain Testability
Domain
Web API
Message
Service
Scheduler
Persistence
Adapter
Command
Adapter
Notification
Adapter
Host Port

42. Advantages - Boundaries
Web API
Message
Service
Scheduler
Domain
Persistence
Adapter
Command
Adapter
Notification
Adapter

43. Advantages - Alternative Adapters
Domain
Web API
Message
Service
Scheduler
Persistence.Adapter Command.Adapter
Notification
Adapter
Host Port
Persistence.Adapter
Csv
Command.Adapter
File

44. Domain
Notification via SMTP
Web API
Message
Service
Scheduler
Persistence
Adapter
Command
Adapter
Notification
Adapter
Host Port

45. Takeaways
● Onion Architecture, Clean Architecture and Ports & Adapters are
essentially the same thing
● Ports are just a name given to a common group of abstractions in your
domain
● Adapters are a group of specific implementations of ports
● Example repository on github for .NET
● Ports & Adapters is an architectural style that will produce framework
independent applications

46. ● http://alistair.cockburn.us/Hexagonal+architecture
● http://blog.ploeh.dk/2013/12/03/layers-onions-ports-adapters-its-all-the-same/
● https://github.com/nrjohnstone/ports-adapters-examples
● https://www.linkedin.com/in/nrjohnstone
● https://nathanjohnstone.wordpress.com/
● n.johnstone@coolblue.nl