Getting Clean, Keeping Lean

Transcript

1. Getting clean.
   Keeping lean.
   

   View Slide

2. @hitherejoe hitherejoe joebirch.co
   Joe Birch - Android Engineer @ Buffer
   

   View Slide

3. @buffer buffer.com
   

   View Slide

4. Greenfield projects
   

   View Slide

5. View Slide

6. - High-level of technical debt
   - Extremely tightly coupled concepts
   - No unit or UI tests
   - Difficult to know what is going on and where
   No longer lean
   

   View Slide

7. - YOU know what is what
   - YOU know where class X is
   - YOU know where logic for Y is
   - But what about along the line…
   No longer lean
   (for now)
   (for now)
   (for now)
   

   View Slide

8. 25
   50
   75
   100
   Output
   Debt
   

   View Slide

9. 25
   50
   75
   100
   Output
   Debt
   

   View Slide

10. For the sake of yours and future
    developers sanity - have
    empathy. Be mindful of the
    consequences and think before
    you craft.
    

    View Slide

11. Buffer for Android
    

    View Slide

12. View Slide

13. View Slide

14. View Slide

15. - Lack of architecture
    - Bloated activities with multiple responsibilities
    - Difficult to test
    - Difficult to extend and maintain
    - Duplication of concepts == no reuse
    

    View Slide

16. Moving to MVP
    - Fear of changing too much
    - Helped separate presentation logic
    - DataManagers to house data operations
    - Increased test coverage
    

    View Slide

17. View Slide

18. View Slide

19. Not enough.
    - Bloated DataManager classes
    - Future changes, offline - where?
    - Presentation linked to specific data source
    - No clear line between responsibilites
    - Buffer is a big app. Data types, features, sources
    

    View Slide

20. Architecture
    “The art of planning, designing and
    constructing buildings”
    

    View Slide

21. Architecture
    “The art of planning, designing and
    constructing buildings concepts”
    

    View Slide

22. View Slide

23. View Slide

24. View Slide

25. View Slide

26. View Slide

27. 
    Think outside of your team.
    

    View Slide

28. Clean Architecture
    

    View Slide

29. View Slide

30. Separation of Concerns
    

    View Slide

31. - Layers are independent of frameworks
    - Code becomes more testable
    - Inner layers independant of UI
    - Inner layers independant of external parties
    Separation of Concerns
    - Bugs more isolated
    

    View Slide

32. View Slide

33. Layer Models
    - Each layer has own Model classes
    - Removes dependancy on external models
    - Easily map with Mapper classes
    

    View Slide

34. ModelA
    Mapper
    Model
    Mapper
    Model
    

    View Slide

35. Enterprise Business Rules
    - Application Business Objects (Entities)
    - Unaffected by operational change
    - Can create before touching any UI
    

    View Slide

36. public class TournamentModel {

    

    public String id;

    public String name;

    @SerializedName("full_name")

    public String status;

    @SerializedName("date_start")

    public String dateStart;

    @SerializedName("date_end")

    public String dateEnd;

    public int size;

    

    }
    

    View Slide

37. Application Business Rules
    - Application specific business rules
    - Uses Cases
    - Affected by operational change
    - Isolated from external concerns
    

    View Slide

38. public class GetSchedules extends UseCase {

    

    private final SchedulesRepository schedulesRepository;

    

    @Inject

    public GetSchedules(SchedulesRepository schedulesRepository) {

    this.schedulesRepository = schedulesRepository;

    }

    

    @Override

    public Single buildUseCaseObservable() {

    return schedulesRepository.getSchedules();

    }

    

    }
    

    View Slide

39. View Slide

40. Use Case
    Interface
    Interface Impl
    Activity
    Application
    Business
    Rules
    Interface
    Adapters
    

    View Slide

41. Interface Adapters
    - Contains MVP architecture of our app
    - Presenters contain ‘callbacks’
    - Views define contract for implementation
    - Mapper converts data from external form
    

    View Slide

42. public class UpdatesPresenter extends BasePresenter
    implements SingleObserver> {
    @Override
    public void onSubscribe(Disposable d) {
    …
    }
    @Override
    public void onSuccess(List matches) {
    …
    }
    @Override
    public void onError(Throwable e) {
    …
    }
    }
    

    View Slide

43. Presenter
    Interface
    Interface Impl
    Activity
    Interface
    Adapters
    Frameworks &
    Drivers
    

    View Slide

44. Frameworks & Drivers
    - UI components (Activities, Fragments)
    - Networking actions (Retrofit)
    - Storage (Cache & DB)
    - Repository Pattern for interacting with these
    

    View Slide

45. Repository
    Interface
    Repository
    Impl
    DataStore
    Interface
    DataStore
    Impl
    DataStore
    Impl
    DataStore
    Factory
    

    View Slide

46. View Slide

47. Layer Boundaries
    - Communication via abstractions (interfaces)
    - No direct name references in inner layers
    - Instead, inner layer provides this interface
    - aka, The Dependancy Inversion Principle
    

    View Slide

48. Not limited to these layers
    Layer 1
    Layer 2
    Layer 3
    Layer 4
    

    View Slide

49. Not limited to these layers
    Layer 1
    Layer 2
    Layer 3
    

    View Slide

50. Not limited to these layers
    Layer 1
    Layer 2
    Layer 3
    Layer 4
    Layer 5
    Layer 6
    

    View Slide

51. Test Coverage
    

    View Slide

52. View Slide

53. Learnings
    

    View Slide

54. Advantages.
    - High percentage of code coverage
    - Incredibly easy to navigate package structure
    - Easier to maintain
    - Allows us to move faster
    - Focused classes and test classes
    

    View Slide

55. - Seperation of concerns
    - Define, Test, Stabilise before UI
    - Futureproof implementations
    - Clear discipline, good practice
    - and more…
    

    View Slide

56. Disadvantages
    - Adds initial overhead
    - Takes time to get used to
    - Can feel overkill for some tasks
    - Difficult to make decisions
    - Conversion of models between layers
    

    View Slide

57. Winston
    Enterprise
    Business
    Rules
    Application
    Business
    Rules
    Interface
    Adapters
    Mobile
    UI
    TV
    UI
    Wear
    UI
    Frameworks &
    Drivers
    

    View Slide

58. Winston
    Enterprise
    Business
    Rules
    Application
    Business
    Rules
    Interface
    Adapters
    Mobile
    UI
    TV
    UI
    Wear
    UI
    Frameworks &
    Drivers
    @hitherejoe hitherejoe joebirch.co
    

    View Slide

59. Resources
    https://overflow.buffer.com/2016/12/22/rebuild-
    android-composer/
    https://github.com/googlesamples/android-
    architecture
    Clean Architecture: A Craftsman's Guide to Software
    Structure and Design (Robert C. Martin)
    

    View Slide