Clean - Moving forward, evolving our architecture

Describing the way our projects evolved over time, from GodActivities to clean architecture. The pitfalls and benefits.

Transcript

1. EVOLVING OUR ARCHITECTURE Kilian Steenman Thomas Middel
3. Example
4. Example
5. Example
6. Example
7. Spaghetti • Hard to make changes • Almost impossible to unit test • Hard to debug • NOT re-usable
8. MVC?
9. MVC? Controller View Model
10. MVC? Controller View Model Presenter View Model
11. MVP (God)Activity Interact with system Data management UI rendering UI event handling UI logic View navigation Interact with model Model View Presenter
12. MVP (God)Activity Interact with system Data management UI rendering UI event handling UI logic View navigation Interact with model Model View Presenter
13. The View public interface AverageFuelPriceView {
 
 void showAveragePrice(final String pAveragePrice);
 
 void showError(final String pError);
 } @Override
 public void showAveragePrice(final String pAveragePrice) {
 mAveragePriceTextView.setText(pAveragePrice);
 }
14. The Presenter public class AverageFuelPricePresenter implements GetGasStationsListener {
 public void onStart() {
 mFuelPriceRepository.loadGasStations(FuelType.Euro95, this); } 
 @Override
 public void onGasStationsLoaded(final List<GasStation> pGasStations) {
 Price averagePrice = calculateAveragePrice(pGasStations); String formattedPrice = formatPrice(averagePrice);
 mAveragePriceView.showAveragePrice(formattedPrice);
 } @Override
 public void onErrorLoadingGasStations() {
 mAveragePriceView.showError( // .. Error message)
 } private Price calculateAveragePrice(final List<GasStation> pGasStations) {
 // .. Calculate average price
 } private String formatPrice(final Price pPrice) {
 // .. Format price to nice String
 } } public void onStart() {
 mGasStationRepository.loadGasStations(FuelType.Euro95, this); }
15. The Presenter public class AverageFuelPricePresenter implements GetGasStationsListener {
 public void onStart() {
 mFuelPriceRepository.loadGasStations(FuelType.Euro95, this); } 
 @Override
 public void onGasStationsLoaded(final List<GasStation> pGasStations) {
 Price averagePrice = calculateAveragePrice(pGasStations); String formattedPrice = formatPrice(averagePrice);
 mAveragePriceView.showAveragePrice(formattedPrice);
 } @Override
 public void onErrorLoadingGasStations() {
 mAveragePriceView.showError( // .. Error message)
 } private Price calculateAveragePrice(final List<GasStation> pGasStations) {
 // .. Calculate average price
 } private String formatPrice(final Price pPrice) {
 // .. Format price to nice String
 } } public void onStart() {
 mGasStationRepository.loadGasStations(FuelType.Euro95, this); }
16. The Presenter public class AverageFuelPricePresenter implements GetGasStationsListener {
 public void onStart() {
 mFuelPriceRepository.loadGasStations(FuelType.Euro95, this); } 
 @Override
 public void onGasStationsLoaded(final List<GasStation> pGasStations) {
 Price averagePrice = calculateAveragePrice(pGasStations); String formattedPrice = formatPrice(averagePrice);
 mAveragePriceView.showAveragePrice(formattedPrice);
 } @Override
 public void onErrorLoadingGasStations() {
 mAveragePriceView.showError( // .. Error message)
 } private Price calculateAveragePrice(final List<GasStation> pGasStations) {
 // .. Calculate average price
 } private String formatPrice(final Price pPrice) {
 // .. Format price to nice String
 } } @Override
 public void onGasStationsLoaded(final List<GasStation> pGasStations) {
 Price averagePrice = calculateAveragePrice(pGasStations); String formattedPrice = formatPrice(averagePrice);
 mAveragePriceView.showAveragePrice(formattedPrice);
 } @Override
 public void onErrorLoadingGasStations() {
 mAveragePriceView.showError( // .. Error message)
 } implements GetGasStationsListener
17. The Presenter public class AverageFuelPricePresenter implements GetGasStationsListener {
 public void onStart() {
 mFuelPriceRepository.loadGasStations(FuelType.Euro95, this); } 
 @Override
 public void onGasStationsLoaded(final List<GasStation> pGasStations) {
 Price averagePrice = calculateAveragePrice(pGasStations); String formattedPrice = formatPrice(averagePrice);
 mAveragePriceView.showAveragePrice(formattedPrice);
 } @Override
 public void onErrorLoadingGasStations() {
 mAveragePriceView.showError( // .. Error message)
 } private Price calculateAveragePrice(final List<GasStation> pGasStations) {
 // .. Calculate average price
 } private String formatPrice(final Price pPrice) {
 // .. Format price to nice String
 } } private Price calculateAveragePrice(final List<GasStation> pGasStations) {
 // .. Calculate average price
 } private String formatPrice(final Price pPrice) {
 // .. Format price to nice String
 }
18. MVP (God)Activity Interact with system Data management UI rendering UI event handling UI logic View navigation Interact with model Model View Presenter
20. Clean Architecture • Independent of • UI • Frameworks • Databases • Webservices • Testable
21. Clean
22. Entities Clean
23. Use Cases Entities Clean
24. Presenters Repositories Use Cases Entities Clean
25. UI Data sources Presenters Repositories Use Cases Entities Clean
26. UI Data sources Presenters Repositories Use Cases Entities Clean
27. UI Data sources Domain Presenters Repositories Use Cases Entities Clean
28. UI Data sources Domain Data Presenters Repositories Use Cases Entities Clean
29. UI Data sources Domain Data Presentation Presenters Repositories Use Cases Entities Clean
30. Clean
31. Clean UseCase
32. Clean Input UseCase
33. Clean Input Output UseCase
34. Clean Input Output UseCase Get parking history for user
35. Clean Input Output UseCase User ID Get parking history for user
36. Clean Input Output UseCase User ID List of parking transactions Get parking history for user
37. Clean Input Output UseCase
38. Stop parking transaction Clean Input Output UseCase
39. Stop parking transaction Clean Input Output UseCase Parking transaction
40. Stop parking transaction Clean Input Output UseCase Parking transaction Succes or Error
41. Clean Input Output UseCase
42. Get average fuel price Clean Input Output UseCase
43. Get average fuel price Clean Input Output UseCase Fuel type
44. Get average fuel price Clean Input Output UseCase Fuel type Average fuel price
45. Example
46. Example
47. Display average fuel price
48. public interface CalculateAverageFuelPriceInput {
 
 void calculateAveragePrice(FuelType pFuelType);
 
 } Display average fuel price Input interface CalculateAverageFuelPriceInput
49. public interface CalculateAverageFuelPriceInput {
 
 void calculateAveragePrice(FuelType pFuelType);
 
 } Display average fuel price Input void calculateAveragePrice(FuelType pFuelType);
50. public interface CalculateAverageFuelPriceInput {
 
 void calculateAveragePrice(FuelType pFuelType);
 
 } Display average fuel price Input
51. public interface CalculateAverageFuelPriceInput {
 
 void calculateAveragePrice(FuelType pFuelType);
 
 } Display average fuel price Input Output public interface CalculateAverageFuelPriceOutput {
 
 void onAveragePriceCalculated(final Price pPrice);
 
 void onErrorCalculatingAveragePrice();
 
 } interface CalculateAverageFuelPriceOutput
52. public interface CalculateAverageFuelPriceInput {
 
 void calculateAveragePrice(FuelType pFuelType);
 
 } Display average fuel price Input Output public interface CalculateAverageFuelPriceOutput {
 
 void onAveragePriceCalculated(final Price pPrice);
 
 void onErrorCalculatingAveragePrice();
 
 } void onAveragePriceCalculated(final Price pPrice);
53. public interface CalculateAverageFuelPriceInput {
 
 void calculateAveragePrice(FuelType pFuelType);
 
 } Display average fuel price Input Output public interface CalculateAverageFuelPriceOutput {
 
 void onAveragePriceCalculated(final Price pPrice);
 
 void onErrorCalculatingAveragePrice();
 
 } void onErrorCalculatingAveragePrice();
54. The use case public class CalculateAverageFuelPriceUseCase implements CalculateAverageFuelPriceInput {
 
 CalculateAverageFuelPriceOutput mCalculateAverageFuelPriceOutput; GasStationRepository mGasStationRepository;
 
 @Override
 public void calculateAveragePrice(final FuelType pFuelType) {
 mGasStationRepository.loadGasStations(pFuelType, new GasStationsLoadedListener() {
 
 @Override
 public void onGasStationsLoaded(final List<GasStation> pGasStations) {
 Price averagePrice = calculateAveragePrice(pGasStations); mCalculateAverageFuelPriceOutput.onAveragePriceCalculated(averagePrice);
 }
 
 @Override
 public void onErrorLoadingGasStations() {
 mCalculateAverageFuelPriceOutput.onErrorCalculatingAveragePrice();
 }
 }); private Price calculateAveragePrice(final List<GasStation> pGasStations) {
 // .. Calculate average price
 } }
55. The use case public class CalculateAverageFuelPriceUseCase implements CalculateAverageFuelPriceInput {
 
 CalculateAverageFuelPriceOutput mCalculateAverageFuelPriceOutput; GasStationRepository mGasStationRepository;
 
 @Override
 public void calculateAveragePrice(final FuelType pFuelType) {
 mGasStationRepository.loadGasStations(pFuelType, new GasStationsLoadedListener() {
 
 @Override
 public void onGasStationsLoaded(final List<GasStation> pGasStations) {
 Price averagePrice = calculateAveragePrice(pGasStations); mCalculateAverageFuelPriceOutput.onAveragePriceCalculated(averagePrice);
 }
 
 @Override
 public void onErrorLoadingGasStations() {
 mCalculateAverageFuelPriceOutput.onErrorCalculatingAveragePrice();
 }
 }); private Price calculateAveragePrice(final List<GasStation> pGasStations) {
 // .. Calculate average price
 } } implements CalculateAverageFuelPriceInput @Override
 public void calculateAveragePrice(final FuelType pFuelType) {
56. The use case public class CalculateAverageFuelPriceUseCase implements CalculateAverageFuelPriceInput {
 
 CalculateAverageFuelPriceOutput mCalculateAverageFuelPriceOutput; GasStationRepository mGasStationRepository;
 
 @Override
 public void calculateAveragePrice(final FuelType pFuelType) {
 mGasStationRepository.loadGasStations(pFuelType, new GasStationsLoadedListener() {
 
 @Override
 public void onGasStationsLoaded(final List<GasStation> pGasStations) {
 Price averagePrice = calculateAveragePrice(pGasStations); mCalculateAverageFuelPriceOutput.onAveragePriceCalculated(averagePrice);
 }
 
 @Override
 public void onErrorLoadingGasStations() {
 mCalculateAverageFuelPriceOutput.onErrorCalculatingAveragePrice();
 }
 }); private Price calculateAveragePrice(final List<GasStation> pGasStations) {
 // .. Calculate average price
 } } mGasStationRepository.loadGasStations(pFuelType, new GasStationsLoadedListener() {
57. The use case public class CalculateAverageFuelPriceUseCase implements CalculateAverageFuelPriceInput {
 
 CalculateAverageFuelPriceOutput mCalculateAverageFuelPriceOutput; GasStationRepository mGasStationRepository;
 
 @Override
 public void calculateAveragePrice(final FuelType pFuelType) {
 mGasStationRepository.loadGasStations(pFuelType, new GasStationsLoadedListener() {
 
 @Override
 public void onGasStationsLoaded(final List<GasStation> pGasStations) {
 Price averagePrice = calculateAveragePrice(pGasStations); mCalculateAverageFuelPriceOutput.onAveragePriceCalculated(averagePrice);
 }
 
 @Override
 public void onErrorLoadingGasStations() {
 mCalculateAverageFuelPriceOutput.onErrorCalculatingAveragePrice();
 }
 }); private Price calculateAveragePrice(final List<GasStation> pGasStations) {
 // .. Calculate average price
 } } Price averagePrice = calculateAveragePrice(pGasStations); private Price calculateAveragePrice(final List<GasStation> pGasStations) {
 // .. Calculate average price
 }
58. The use case public class CalculateAverageFuelPriceUseCase implements CalculateAverageFuelPriceInput {
 
 CalculateAverageFuelPriceOutput mCalculateAverageFuelPriceOutput; GasStationRepository mGasStationRepository;
 
 @Override
 public void calculateAveragePrice(final FuelType pFuelType) {
 mGasStationRepository.loadGasStations(pFuelType, new GasStationsLoadedListener() {
 
 @Override
 public void onGasStationsLoaded(final List<GasStation> pGasStations) {
 Price averagePrice = calculateAveragePrice(pGasStations); mCalculateAverageFuelPriceOutput.onAveragePriceCalculated(averagePrice);
 }
 
 @Override
 public void onErrorLoadingGasStations() {
 mCalculateAverageFuelPriceOutput.onErrorCalculatingAveragePrice();
 }
 }); private Price calculateAveragePrice(final List<GasStation> pGasStations) {
 // .. Calculate average price
 } } mCalculateAverageFuelPriceOutput.onAveragePriceCalculated(averagePrice); mCalculateAverageFuelPriceOutput.onErrorCalculatingAveragePrice(); CalculateAverageFuelPriceOutput mCalculateAverageFuelPriceOutput;
59. The presenter public class AveragePricePresenter implements CalculateAverageFuelPriceOutput {
 
 AveragePriceView mAveragePriceView;
 
 AverageFuelPriceUseCase mAverageFuelPriceUseCase;
 
 public void loadAveragePrice() {
 mAverageFuelPriceUseCase.getAverageFuelPrice(FuelType.Euro95);
 }
 
 @Override
 public void onAveragePriceCalculated(final Price pPrice) {
 mAveragePriceView.showAveragePrice(formatPrice(pPrice));
 }
 
 @Override
 public void onErrorCalculatingAveragePrice() {
 mAveragePriceView.showError(”Unable to calculate average price”)
 }
 }
60. The presenter public class AveragePricePresenter implements CalculateAverageFuelPriceOutput {
 
 AveragePriceView mAveragePriceView;
 
 AverageFuelPriceUseCase mAverageFuelPriceUseCase;
 
 public void loadAveragePrice() {
 mAverageFuelPriceUseCase.getAverageFuelPrice(FuelType.Euro95);
 }
 
 @Override
 public void onAveragePriceCalculated(final Price pPrice) {
 mAveragePriceView.showAveragePrice(formatPrice(pPrice));
 }
 
 @Override
 public void onErrorCalculatingAveragePrice() {
 mAveragePriceView.showError(”Unable to calculate average price”)
 }
 } implements CalculateAverageFuelPriceOutput @Override
 public void onAveragePriceCalculated(final Price pPrice) {
 mAveragePriceView.showAveragePrice(formatPrice(pPrice));
 }
 
 @Override
 public void onErrorCalculatingAveragePrice() {
 mAveragePriceView.showError(”Unable to calculate average price”)
 }

61. Clean Architecture Presenter View Use Case Entities
62. What are the benefits? • Re-usable • Unit testable • Easy to change
63. Example Show Toast instead of text bar
64. Example Show Toast instead of text bar @Override
 public void showAveragePrice(final String pAveragePrice) {
 mAveragePriceTextView.setText(pAveragePrice);
 }
65. Example Show Toast instead of text bar @Override
 public void showAveragePrice(final String pAveragePrice) {
 mAveragePriceTextView.setText(pAveragePrice);
 } @Override
 public void showAveragePrice(final String pAveragePrice) {
 Toast.makeText(this, pAveragePrice, Toast.LENGTH_SHORT).show();
 }
66. UI Data sources Presenters Repositories Example Show Toast instead of text bar @Override
 public void showAveragePrice(final String pAveragePrice) {
 mAveragePriceTextView.setText(pAveragePrice);
 } @Override
 public void showAveragePrice(final String pAveragePrice) {
 Toast.makeText(this, pAveragePrice, Toast.LENGTH_SHORT).show();
 } Entities Use cases Abstraction
67. Example Load average price from webservice
68. Example Load average price from webservice public class CalculateAverageFuelPriceUseCase implements CalculateAverageFuelPriceInput {
 
 GasStationRepository mGasStationRepository; 
 @Override
 public void calculateAveragePrice(final FuelType pFuelType) {
 mGasStationRepository.loadGasStations(pFuelType, new GasStationsLoadedListener() { // .. Code that calculates the average price
 } } GasStationRepository mGasStationRepository; mGasStationRepository.loadGasStations(pFuelType, new GasStationsLoadedListener() {
69. Example Load average price from webservice public class CalculateAverageFuelPriceUseCase implements CalculateAverageFuelPriceInput {
 
 GasStationRepository mGasStationRepository; 
 @Override
 public void calculateAveragePrice(final FuelType pFuelType) {
 mGasStationRepository.loadGasStations(pFuelType, new GasStationsLoadedListener() { // .. Code that calculates the average price
 } } GasStationRepository mGasStationRepository; mGasStationRepository.loadGasStations(pFuelType, new GasStationsLoadedListener() {
70. Example Load average price from webservice public class CalculateAverageFuelPriceUseCase implements CalculateAverageFuelPriceInput {
 
 GasStationRepository mGasStationRepository; 
 @Override
 public void calculateAveragePrice(final FuelType pFuelType) {
 mGasStationRepository.loadGasStations(pFuelType, new GasStationsLoadedListener() { // .. Code that calculates the average price
 } } UI Data sources Presenters Repositories Entities Use cases
71. Example Show loading state public interface AverageFuelPriceView {
 
 void showAveragePrice(final String pAveragePrice);
 
 void showError(String pError); 
 }
72. Example Show loading state public interface AverageFuelPriceView {
 
 void showAveragePrice(final String pAveragePrice);
 
 void showError(String pError); 
 } void showLoading(); void hideLoading();
73. public class AveragePricePresenter implements CalculateAverageFuelPriceOutput {
 
 AveragePriceView mAveragePriceView;
 
 AverageFuelPriceUseCase mAverageFuelPriceUseCase;
 
 public void loadAveragePrice() {
 mAveragePriceView.showLoading();
 mAverageFuelPriceUseCase.getAverageFuelPrice(FuelType.Euro95);
 }
 
 @Override
 public void onAveragePriceCalculated(final Price pPrice) {
 mAveragePriceView.hideLoading();
 mAveragePriceView.showAveragePrice(formatPrice(pPrice));
 }
 
 @Override
 public void onErrorCalculatingAveragePrice() {
 mAveragePriceView.hideLoading();
 mAveragePriceView.showError(”Error message”)
 }
 } Example Show loading state
74. public class AveragePricePresenter implements CalculateAverageFuelPriceOutput {
 
 AveragePriceView mAveragePriceView;
 
 AverageFuelPriceUseCase mAverageFuelPriceUseCase;
 
 public void loadAveragePrice() {
 mAveragePriceView.showLoading();
 mAverageFuelPriceUseCase.getAverageFuelPrice(FuelType.Euro95);
 }
 
 @Override
 public void onAveragePriceCalculated(final Price pPrice) {
 mAveragePriceView.hideLoading();
 mAveragePriceView.showAveragePrice(formatPrice(pPrice));
 }
 
 @Override
 public void onErrorCalculatingAveragePrice() {
 mAveragePriceView.hideLoading();
 mAveragePriceView.showError(”Error message”)
 }
 } Example Show loading state mAveragePriceView.showLoading(); mAveragePriceView.hideLoading(); mAveragePriceView.hideLoading(); loadAveragePrice() onAveragePriceCalculated(final Price pPrice) onErrorCalculatingAveragePrice()
75. public class AveragePricePresenter implements CalculateAverageFuelPriceOutput {
 
 AveragePriceView mAveragePriceView;
 
 AverageFuelPriceUseCase mAverageFuelPriceUseCase;
 
 public void loadAveragePrice() {
 mAveragePriceView.showLoading();
 mAverageFuelPriceUseCase.getAverageFuelPrice(FuelType.Euro95);
 }
 
 @Override
 public void onAveragePriceCalculated(final Price pPrice) {
 mAveragePriceView.hideLoading();
 mAveragePriceView.showAveragePrice(formatPrice(pPrice));
 }
 
 @Override
 public void onErrorCalculatingAveragePrice() {
 mAveragePriceView.hideLoading();
 mAveragePriceView.showError(”Error message”)
 }
 } Example Show loading state mAveragePriceView.showLoading(); mAveragePriceView.hideLoading(); mAveragePriceView.hideLoading(); loadAveragePrice() onAveragePriceCalculated(final Price pPrice) onErrorCalculatingAveragePrice() UI Data sources Presenters Repositories Entities Use cases
76. RxJava
77. RxJava Combine input/output boundaries
78. public interface
 } void calculateAveragePrice(FuelType pFuelType); RxJava Combine input/output boundaries public interface CalculateAverageFuelPriceOutput {
 
 void onAveragePriceCalculated(final Price pPrice);
 
 void onErrorCalculatingAveragePrice();
 
 } Price CalculateAverageFuelPriceInput {
79. public interface
 } void calculateAveragePrice(FuelType pFuelType); Observable< > RxJava Combine input/output boundaries public interface CalculateAverageFuelPriceOutput {
 
 void onAveragePriceCalculated(final Price pPrice);
 
 void onErrorCalculatingAveragePrice();
 
 } Price CalculateAverageFuelPrice {
80. RxJava Managing subscriptions public class AveragePricePresenter implements CalculateAverageFuelPriceOutput {
 
 Subscription mSubscription;
 
 public void loadAveragePrice() {
 mSubscription = mAverageFuelPriceUseCase.
 // RxStuff
 .subscribe(// Subscription handling)
 }
 
 public void onPause() {
 mSubscription.unsubscribe();
 } }
81. RxJava Managing subscriptions public class AveragePricePresenter implements CalculateAverageFuelPriceOutput {
 
 Subscription mSubscription;
 
 public void loadAveragePrice() {
 mSubscription = mAverageFuelPriceUseCase.
 // RxStuff
 .subscribe(// Subscription handling)
 }
 
 public void onPause() {
 mSubscription.unsubscribe();
 } } public void onPause() {
 mSubscription.unsubscribe();
 } public void loadAveragePrice() {
 mSubscription = mAverageFuelPriceUseCase.
 // RxStuff
 .subscribe(// Subscription handling)
 }
82. Next steps • Rx view input • Model View Intent (MVI)
83. Recommended watching Architecture The Lost Years - Robert C. Martin (Uncle Bob) Managing State with RxJava - Jake Wharton Architecting Android - Fernando Cejas