Application Architecture for Droids

Exploring MVP architecture patterns for Android in the Star Wars universe.

Transcript

1. FOR DROIDS APPLICATION ARCHITECTURE
2. JOSH KOVACH @shekibobo #IOextendedGR
3. @shekibobo #IOextendedGR @shekibobo #IOextendedGR
4. @shekibobo #IOextendedGR "Fear will keep the local systems in line."
5. @shekibobo #IOextendedGR
6. @shekibobo #IOextendedGR
7. @shekibobo #IOextendedGR SEPARATION OF CONCERNS DESIGN TO INTERFACES
8. @shekibobo #IOextendedGR REUSABILITY
9. @shekibobo #IOextendedGR MODEL PRESENTER VIEW
10. @shekibobo #IOextendedGR MODEL ‣ Network API - Client, Data Model ‣ Persistence API - Database, Preferences, System Services ‣ Domain Model - Business Logic, Rules, Interactions
11. @shekibobo #IOextendedGR MODEL
12. @shekibobo #IOextendedGR MODEL PRESENTER VIEW
13. @shekibobo #IOextendedGR VIEW ‣ Update UI from information passed by presenter ‣ Route user interactions to the presenter
14. @shekibobo #IOextendedGR VIEW
15. @shekibobo #IOextendedGR MODEL PRESENTER VIEW
16. @shekibobo #IOextendedGR PRESENTER ‣ Routing between view and model layer ‣ Listen for predefined actions from the view ‣ Route actions to the appropriate model ‣ Publish new information to the view
17. @shekibobo #IOextendedGR PRESENTER
18. @shekibobo #IOextendedGR
19. @shekibobo #IOextendedGR class LightSaberMVP { } interface View { } fun showHilt(hiltImageUrl: String) fun showBlade(color: Int, length: Int) fun hideBlade() interface Presenter { } fun attach() fun detach() fun activate() fun deactivate() class LightSaberPresenter: LightSaberMVP.Presenter interface LightSaberPresenterImpl: LightSaberPresenter
20. @shekibobo #IOextendedGR class LightSaberPresenter( val view: View, val lightsaber: LightSaber ) : LightSaberMVP.Presenter { override fun attach() { this.view.showHilt(lightsaber.imageUrl) } override fun detach() { deactivate() } override fun activate() { lightsaber.activate() view.showBlade(lightsaber.color, lightsaber.length) } override fun deactivate() { lightsaber.deactivate() view.hideBlade() } }
21. @shekibobo #IOextendedGR class LightSaberMVP { } interface View { } fun showHilt(hiltImageUrl: String) fun showBlade(color: Int, length: Int) fun hideBlade() interface Presenter { } fun attach() fun detach() fun activate() fun deactivate()
22. @shekibobo #IOextendedGR class LightSaberActivity : AppCompatActivity(), LightSaberMVP.View { @Inject lateinit var lightsaberPresenter: LightSaberPresenter @BindView(R.id.activator) lateinit var activator: Switch @BindView(R.id.bladeView) lateinit var bladeView: ImageView @BindView(R.id.hiltView) lateinit var hiltView: ImageView override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_lightsaber) ButterKnife.bind(this) } @OnCheckedChanged(R.id.activator) fun activatorChanged(isChecked: Boolean) { if (isChecked) lightsaberPresenter.activate() else lightsaberPresenter.deactivate() } override fun onResume() { super.onResume() lightsaberPresenter.attach() } override fun onPause() { lightsaberPresenter.detach() super.onPause() } override fun showHilt(hiltImageUrl: String) { hiltView.loadFromUrl(hiltImageUrl) } override fun showBlade(color: Int, length: Int) { bladeView.setBackgroundColor(color) bladeView.layoutParams = ViewGroup.LayoutParams(bladeView.layoutParams).apply { this.height = length } } override fun hideBlade() { bladeView.layoutParams = ViewGroup.LayoutParams(bladeView.layoutParams).apply { this.height = 0 } } }
23. @shekibobo #IOextendedGR class LightSaberActivity : AppCompatActivity(), LightSaberMVP.View { @Inject lateinit var lightsaberPresenter: LightSaberPresenter @BindView(R.id.activator) lateinit var activator: Switch @BindView(R.id.bladeView) lateinit var bladeView: ImageView @BindView(R.id.hiltView) lateinit var hiltView: ImageView override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_lightsaber) ButterKnife.bind(this) } @OnCheckedChanged(R.id.activator) fun activatorChanged(isChecked: Boolean) { if (isChecked) lightsaberPresenter.activate() else lightsaberPresenter.deactivate() }
24. @shekibobo #IOextendedGR class LightSaberActivity : AppCompatActivity(), LightSaberMVP.View { @Inject lateinit var lightsaberPresenter: LightSaberPresenter @BindView(R.id.activator) lateinit var activator: Switch @BindView(R.id.bladeView) lateinit var bladeView: ImageView @BindView(R.id.hiltView) lateinit var hiltView: ImageView override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_lightsaber) ButterKnife.bind(this) } @OnCheckedChanged(R.id.activator) fun activatorChanged(isChecked: Boolean) { if (isChecked) lightsaberPresenter.activate() else lightsaberPresenter.deactivate() } override fun onResume() { super.onResume() lightsaberPresenter.attach()
25. @shekibobo #IOextendedGR @OnCheckedChanged(R.id.activator) fun activatorChanged(isChecked: Boolean) { if (isChecked) lightsaberPresenter.activate() else lightsaberPresenter.deactivate() } override fun onResume() { super.onResume() lightsaberPresenter.attach() } override fun onPause() { lightsaberPresenter.detach() super.onPause() } override fun showHilt(hiltImageUrl: String) { hiltView.loadFromUrl(hiltImageUrl) }
26. override fun onPause() { lightsaberPresenter.detach() super.onPause() } override fun showHilt(hiltImageUrl: String) { hiltView.loadFromUrl(hiltImageUrl) } override fun showBlade(color: Int, length: Int) { bladeView.setBackgroundColor(color) bladeView.layoutParams = ViewGroup.LayoutParams(bladeView.layoutParams).apply { this.height = length } } override fun hideBlade() { bladeView.layoutParams = ViewGroup.LayoutParams(bladeView.layoutParams).apply { this.height = 0 } } } @shekibobo #IOextendedGR
27. class LightSaberActivity : AppCompatActivity(), LightSaberMVP.View { @Inject lateinit var lightsaberPresenter: LightSaberPresenter @BindView(R.id.activator) lateinit var activator: Switch @BindView(R.id.bladeView) lateinit var bladeView: ImageView @BindView(R.id.hiltView) lateinit var hiltView: ImageView override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_lightsaber) ButterKnife.bind(this) } @OnCheckedChanged(R.id.activator) fun activatorChanged(isChecked: Boolean) { if (isChecked) lightsaberPresenter.activate() else lightsaberPresenter.deactivate() } override fun onResume() { super.onResume() lightsaberPresenter.attach() } override fun onPause() { lightsaberPresenter.detach() super.onPause() } override fun showHilt(hiltImageUrl: String) { hiltView.loadFromUrl(hiltImageUrl) } override fun showBlade(color: Int, length: Int) { bladeView.setBackgroundColor(color) bladeView.layoutParams = ViewGroup.LayoutParams(bladeView.layoutParams).apply { this.height = length } } override fun hideBlade() { bladeView.layoutParams = ViewGroup.LayoutParams(bladeView.layoutParams).apply { this.height = 0 } } } @shekibobo #IOextendedGR MAP USER INPUTS TO PRESENTER ACTIONS ONLY DOES VIEW STUFF ZERO BUSINESS LOGIC
28. @shekibobo #IOextendedGR
29. @shekibobo #IOextendedGR MOCK DEPENDENCIES RUN CODE ASSERT INTERACTIONS TESTING
30. @shekibobo #IOextendedGR @Test @Throws(Exception ::class) fun attach_displaysLightsaberHilt() { val view = mock<LightSaberMVP.View>() val presenter = LightSaberPresenter(view, lightsaber) presenter.attach() verify(view).showHilt(lightsaber.imageUrl) } @Test @Throws(Exception ::class) fun activate_tellsViewToShowBlade() { val view = mock<LightSaberMVP.View>() val presenter = LightSaberPresenter(view, lightsaber).apply { attach() } presenter.activate() verify(view).showBlade(Color.RED, 800) } @Test @Throws(Exception ::class) fun deactivate_tellsViewToHideBlade() { val view = mock<LightSaberMVP.View>() val presenter = LightSaberPresenter(view, lightsaber).apply { attach() activate() } presenter.deactivate() verify(view).hideBlade() }
31. @shekibobo #IOextendedGR @Test fun onAttach_togglesLoadingWhileFetchingClaimsFromServer() { val view = mock<ClaimsPresenter.View>() val api = mock<DonutsApi>() whenever(api.getTodayClaims()).thenReturn(Observable.just(listOf())) val presenter = ClaimsPresenter(view, api) presenter.onAttach() val inOrder = inOrder(view, api) inOrder.verify(view).showLoading(true) inOrder.verify(api).getTodayClaims() inOrder.verify(view).showLoading(false) inOrder.verify(view).showNoUsers() } https://collectiveidea.com/blog
32. @shekibobo #IOextendedGR @Test @Throws(Exception ::class) fun attach_displaysLightsaberHilt() { val view = mock<LightSaberMVP.View>() val presenter = LightSaberPresenter(view, lightsaber) presenter.attach() verify(view).showHilt(lightsaber.imageUrl) } @Test @Throws(Exception ::class) fun activate_tellsViewToShowBlade() { val view = mock<LightSaberMVP.View>() val presenter = LightSaberPresenter(view, lightsaber).apply { attach() } presenter.activate() verify(view).showBlade(Color.RED, 800) } @Test @Throws(Exception ::class) fun deactivate_tellsViewToHideBlade() { val view = mock<LightSaberMVP.View>() val presenter = LightSaberPresenter(view, lightsaber).apply { attach() activate() } presenter.deactivate() verify(view).hideBlade() }
33. @shekibobo #IOextendedGR @Test @Throws(Exception ::class) fun attach_displaysLightsaberHilt() { val view = mock<LightSaberMVP.View>() val api = mock<LightSaberAPI>() val presenter = LightSaberPresenter(view, lightsaber, api) presenter.attach() verify(view).showHilt(lightsaber.imageUrl) } @Test @Throws(Exception ::class) fun activate_tellsViewToShowBlade() { val view = mock<LightSaberMVP.View>() val api = mock<LightSaberAPI>() val presenter = LightSaberPresenter(view, lightsaber, api).apply { attach() } presenter.activate() verify(view).showBlade(Color.RED, 800) } @Test @Throws(Exception ::class) fun deactivate_tellsViewToHideBlade() { val view = mock<LightSaberMVP.View>() val api = mock<LightSaberAPI>() val presenter = LightSaberPresenter(view, lightsaber, api).apply { attach() activate() } presenter.deactivate() verify(view).hideBlade() }
34. @shekibobo #IOextendedGR class LightSaberPresenter( val view: View, val lightsaber: LightSaber ) : LightSaberMVP.Presenter { override fun attach() { this.view.showHilt(lightsaber.imageUrl) } override fun detach() { deactivate() } override fun activate() { lightsaber.activate() view.showBlade(lightsaber.color, lightsaber.length) } override fun deactivate() { lightsaber.deactivate() view.hideBlade() } }
35. @shekibobo #IOextendedGR class LightSaberPresenter( val view: View, val lightsaber: LightSaber, val lightsaberAPI: LightSaberAPI ) : LightSaberMVP.Presenter { override fun attach() { this.view.showHilt(lightsaber.imageUrl) } override fun detach() { deactivate() } override fun activate() { lightsaberAPI.activate(lightsaber) .subscribe { view.showBlade(lightsaber.color, lightsaber.length) } } override fun deactivate() { lightsaberAPI.deactivate(lightsaber) .subscribe { view.hideBlade() } } }
36. @shekibobo #IOextendedGR class LightSaberActivity : AppCompatActivity(), LightSaberMVP.View { @Inject lateinit var lightsaberPresenter: LightSaberPresenter @BindView(R.id.activator) lateinit var activator: Switch @BindView(R.id.bladeView) lateinit var bladeView: ImageView @BindView(R.id.hiltView) lateinit var hiltView: ImageView override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_lightsaber) ButterKnife.bind(this) } @OnCheckedChanged(R.id.activator) fun activatorChanged(isChecked: Boolean) { if (isChecked) lightsaberPresenter.activate() else lightsaberPresenter.deactivate() } override fun onResume() { super.onResume() lightsaberPresenter.attach() } override fun onPause() { lightsaberPresenter.detach() super.onPause() } override fun showHilt(hiltImageUrl: String) { hiltView.loadFromUrl(hiltImageUrl) } override fun showBlade(color: Int, length: Int) { bladeView.setBackgroundColor(color) bladeView.layoutParams = ViewGroup.LayoutParams(bladeView.layoutParams).apply { this.height = length } } override fun hideBlade() { bladeView.layoutParams = ViewGroup.LayoutParams(bladeView.layoutParams).apply { this.height = 0 } } }
37. @shekibobo #IOextendedGR
38. @shekibobo #IOextendedGR Implementation Details ‣ There are no standards. ‣ Common patterns with varying conventions. ‣ There is no One True Way™* * yet
39. interface Presenter { } fun onCreate() fun onResume() fun onPause() fun onDestroy() fun onActivated() fun onDeactivated() @shekibobo #IOextendedGR Implementation Details interface Presenter { } fun attach() fun detach() fun activate() fun deactivate() interface Presenter { } fun onAttached() fun onDetached() fun onActivated() fun onDeactivated()
40. @shekibobo #IOextendedGR Implementation Details - Lifecycle interface Presenter { } fun attach() fun detach() fun activate() fun deactivate() interface Presenter { } fun attach(view: View) fun detach(cache: Bool = false) fun activate() fun deactivate()
41. @shekibobo #IOextendedGR Implementation Details - Lifecycle interface Presenter { } fun attach() fun detach() fun activate() fun deactivate() ‣ Usage: ‣ Presenter owned by View. ‣ Update view as soon as it's attached. ‣ Detach view to cancel or cache.
42. @shekibobo #IOextendedGR Implementation Details - Lifecycle interface Presenter { } fun attach() fun detach() fun activate() fun deactivate() ‣ Benefits: ‣ View is @Nonnull. ‣ Fewer paths to test. ‣ Does not need to track state. ‣ Downsides: ‣ Long-running processes are lost.
43. @shekibobo #IOextendedGR Implementation Details - Lifecycle interface Presenter { } fun attach() fun detach() fun activate() fun deactivate() interface Presenter { } fun attach(view: View) fun detach(cache: Bool = false) fun activate() fun deactivate()
44. @shekibobo #IOextendedGR CONFIGURATION CHANGE
45. @shekibobo #IOextendedGR Implementation Details - Lifecycle interface Presenter { } fun attach(view: View) fun detach(cache: Bool = false) fun activate() fun deactivate() ‣ Usage: ‣ Presenter created without view. ‣ Weak reference to view bound in Activity.onCreate(). ‣ Persisted in PresenterCache when detached.
46. @shekibobo #IOextendedGR Implementation Details - Lifecycle interface Presenter { } fun attach(view: View) fun detach(cache: Bool = false) fun activate() fun deactivate() ‣ Benefits: ‣ Lifecycle independence. ‣ Can be cached in @ApplicationScope PresenterCache. ‣ Downsides: ‣ Presenter owns state instead of model. ‣ View is @Nullable. ‣ Extra testing steps and scenarios. ‣ Attach has important side-effects that complicate testing.
47. @shekibobo #IOextendedGR Implementation Details - Model ‣ Long-running processes are lost. REPOSITORY
48. @shekibobo #IOextendedGR Implementation Details - Model ‣ Smarter model. ‣ Manages in-flight requests outside Activity. ‣ Presenter subscribes to updates from repository. REPOSITORY
49. @shekibobo #IOextendedGR Implementation Details - View ‣ Usage: ‣ showThing(thing: Thing) ‣ showError(throwable: Error) ‣ showLoading(isLoading: Bool, progress: Float) ‣ navigateTo(resource: T) interface View { } fun showHilt(hiltImageUrl: String) fun showBlade(color: Int, length: Int) fun hideBlade()
50. @shekibobo #IOextendedGR A NEW NEW HOPE?
51. @shekibobo #IOextendedGR RESOURCES Artwork Ralph McQuarrie Mark Molnar
 Lucasfilm Ltd Charles Woods
 swmand4
 Further Reading Presenters are Not for Persisting
 https://hackernoon.com/presenters-are-not-for-persisting-f537a2cc7962 
 Model-View-Presenter: Android Guidelines
 https://medium.com/@cervonefrancesco/model-view-presenter-android-guidelines-94970b430ddf 
 Clean Architecture with Kotlin + RxJava + Dagger 2
 https://medium.com/uptech-team/clean-architecture-in-android-with-kotlin-rxjava-dagger-2-2fdc7441edfc