Networking and Persistence in Mobile Apps at Scale

In this talk, I present the concept of a Model Store. This is a black-box system which maintains up-to-date model information for a dynamic app. It necessarily has networking, persistence, caching, and change notification capabilities. Through a series of slides and code examples, I illustrate how a well-designed codebase which includes one or more Model Stores can help developers attain a more well-reasoned and high-quality app.

Transcript

1. Jake Schwartz Networking and Persistence for Mobile Jake Schwartz Mobile @ Life360
2. Jake Schwartz (The Web in 1998)
3. Jake Schwartz • Top 10 Social Networking app • Over 10 million MAU • 13 languages Jake Schwartz
4. Jake Schwartz
5. Jake Schwartz 1.7 billion mobile API requests / day
6. Jake Schwartz Mobile Challenges Model Store Internals
7. Jake Schwartz Mobile Challenges Model Store Internals
8. Jake Schwartz Mobile Challenges • Mobile data usage • Battery consumption • Caching • Updating underlying technologies
9. Jake Schwartz Core Data Realm
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11. Jake Schwartz …
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13. Jake Schwartz …
14. Jake Schwartz 2 Years
15. Jake Schwartz User-facing features Networking & persistence
16. Jake Schwartz Bicameral Codebase User-facing features Networking & persistence
17. Jake Schwartz Bicameral Codebase Core Data HTTP API WebSockets Older database Offline mode Cached avatar images Map Pins Chat UI User Profile Circle switcher Loading animation
18. Jake Schwartz Bicameral Codebase User-facing features Model Store
19. Jake Schwartz Model Store
20. Jake Schwartz Model Store Network syncing Persistence Fetching Change notifications Mutation
21. Jake Schwartz Model Store Network syncing Persistence Data stream Mutation
22. Jake Schwartz MemberStore Syncing Members Persisting Members Member data stream Mutating Members
23. Jake Schwartz Model Store “Maintaining your data, so the rest of your app doesn’t have to”
24. Jake Schwartz
25. Jake Schwartz private let modelStore = ModelStore(.coreData, .webSockets) modelStore.getAllMembers() .map { member: Member -> MapPin in let mapPin = MapPin( coord: member.coordinate, avatarURL: member.avatarURL, firstName: member.firstName ) return mapPin } .subscribe(onNext: { mapPin in mapView.updatePin(for: mapPin.ID, mapPin) }) .disposed(by: disposeBag)
26. Jake Schwartz private let modelStore = ModelStore(.coreData, .webSockets) private let modelStore = ModelStore(.coreData, .webSockets) modelStore.getAllMembers() .map { member: Member -> MapPin in let mapPin = MapPin( coord: member.coordinate, avatarURL: member.avatarURL, firstName: member.firstName ) return mapPin } .subscribe(onNext: { mapPin in mapView.updatePin(for: mapPin.ID, mapPin) }) .disposed(by: disposeBag)
27. Jake Schwartz modelStore.getAllMembers() .map { member: Member -> MapPin in } private let modelStore = ModelStore(.coreData, .webSockets) modelStore.getAllMembers() .map { member: Member -> MapPin in let mapPin = MapPin( coord: member.coordinate, avatarURL: member.avatarURL, firstName: member.firstName ) return mapPin } .subscribe(onNext: { mapPin in mapView.updatePin(for: mapPin.ID, mapPin) }) .disposed(by: disposeBag)
28. Jake Schwartz let mapPin = MapPin( coord: member.coordinate, avatarURL: member.avatarURL, firstName: member.firstName ) return mapPin private let modelStore = ModelStore(.coreData, .webSockets) modelStore.getAllMembers() .map { member: Member -> MapPin in let mapPin = MapPin( coord: member.coordinate, avatarURL: member.avatarURL, firstName: member.firstName ) return mapPin } .subscribe(onNext: { mapPin in mapView.updatePin(for: mapPin.ID, mapPin) }) .disposed(by: disposeBag)
29. Jake Schwartz .subscribe(onNext: { mapPin in mapView.updatePin(for: mapPin.ID, mapPin) }) private let modelStore = ModelStore(.coreData, .webSockets) modelStore.getAllMembers() .map { member: Member -> MapPin in let mapPin = MapPin( coord: member.coordinate, avatarURL: member.avatarURL, firstName: member.firstName ) return mapPin } .subscribe(onNext: { mapPin in mapView.updatePin(for: mapPin.ID, mapPin) }) .disposed(by: disposeBag)
30. Jake Schwartz private let modelStore = ModelStore(.coreData, .webSockets) modelStore.getAllMembers() .map { member: Member -> MapPin in let mapPin = MapPin( coord: member.coordinate, avatarURL: member.avatarURL, firstName: member.firstName ) return mapPin } .subscribe(onNext: { mapPin in mapView.updatePin(for: mapPin.ID, mapPin) }) .disposed(by: disposeBag)
31. Jake Schwartz Bicameral Codebase UI Code Model Store
32. Jake Schwartz Bicameral Codebase Rocks Decoupled code Fewer bugs Faster feature development Skill specialization Hiring
33. Jake Schwartz Mobile Challenges Model Store Internals
34. Jake Schwartz Mobile Challenges Model Store Internals
35. Jake Schwartz Internals LocalStore RemoteStore
36. Jake Schwartz Model Store
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38. Jake Schwartz
39. Jake Schwartz public protocol ModelStore { associatedtype ModelType: EntityType func activate() func deactivate() func create(entity: ModelType) -> Observable<Result<ModelType>> var entities: Observable<[ModelType]> { get } func entity(forID entityID: EntityID) -> Observable<ModelType?> func update(entity: ModelType) -> Observable<Result<ModelType>> func delete(id: EntityID) -> Observable<Result<ModelType>> }
40. Jake Schwartz public protocol ModelStore { associatedtype ModelType: EntityType func activate() func deactivate() func create(entity: ModelType) -> Observable<Result<ModelType>> var entities: Observable<[ModelType]> { get } func entity(forID entityID: EntityID) -> Observable<ModelType?> func update(entity: ModelType) -> Observable<Result<ModelType>> func delete(id: EntityID) -> Observable<Result<ModelType>> }
41. Jake Schwartz public protocol ModelStore { associatedtype ModelType: EntityType func activate() func deactivate() func create(entity: ModelType) -> Observable<Result<ModelType>> var entities: Observable<[ModelType]> { get } func entity(forID entityID: EntityID) -> Observable<ModelType?> func update(entity: ModelType) -> Observable<Result<ModelType>> func delete(id: EntityID) -> Observable<Result<ModelType>> }
42. Jake Schwartz public protocol ModelStore { associatedtype ModelType: EntityType func activate() func deactivate() func create(entity: ModelType) -> Observable<Result<ModelType>> var entities: Observable<[ModelType]> { get } func entity(forID entityID: EntityID) -> Observable<ModelType?> func update(entity: ModelType) -> Observable<Result<ModelType>> func delete(id: EntityID) -> Observable<Result<ModelType>> }
43. Jake Schwartz Model Store
44. Jake Schwartz Mobile Challenges Model Store Internals
45. Jake Schwartz
46. Jake Schwartz
47. Jake Schwartz
48. Jake Schwartz iOS + Android • Doubled our team’s software design capacity • Shared wiki documents • Architecture diagram • API definitions
49. Jake Schwartz Platform Parity RxSwift & RxJava Realm DB Architecture
50. Jake Schwartz Mobile Challenges Model Store Internals
51. Jake Schwartz engineering.life360.com jake@life360.com