Android reactive programming using agera
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1. Agera is a lightweight Android library for reactive programming developed by Google Play Music Team. It uses four interfaces - Observable, Supplier, Receiver, and Updatable to implement the reactive pattern. 2. Repositories are observable objects that supply data and define events as changes to the supplied data. There are simple repositories like static and mutable repositories, and complex repositories that listen to changes in other repositories. 3. Compiled repositories initialize complex repositories in one expression by specifying data sources, processing flow using operators like map and filter, and configurations like error handling. They return reactive sequences to notify subscribers of data changes.
Android reactive programming using agera
- 2. Android Reactive programming using Agera Mahmoud El-Naggar
- 3. Content • Reactive programming • Agera Basics • Repositories • Compiled repositories • Compiled functions • Reservoirs and parallelism • Agera and Retrofit • Agera vs RxJava • References
- 4. Asynchronous Stream It Is Writing asynchronous and event/data stream programs using observable sequences
- 5. Reactive programming Observable Pattern : Is Using to notify a group of listeners about data change.
- 7. Reactive Systems Characteristics : 1- Responsive : The application always respond to user actions. 2- Resilient : The application is responsive on state of failure. 3- Elastic : Must be responsive when data scale and increase resources. 4- Message-Driven : Reactive programs depends on Async messages passing when data changes or event occur to apply isolation and loose coupling between components.
- 8. Reactive Implementations on Android 1. Google Agera : Push event, pull data Model 2. RxJava & RxAndroid : Push event, pull data Model 3. EventBus & Otto : publisher/subscriber
- 9. Reactive Programming and Data Streaming Library
- 10. Agera Basics Google Agera : Agera (Swedish for “to act”) is lightweight Android library for Reactive Programming Implemented by Google Play Music Team. Agera uses four Interfaces to implement Reactive programming : 1. Observable : to add and remove Updatables 2. Supplier<T>: to supply data to Updatables 3. Receiver<T> : to get data from Supplier 4. Updatable : Object which be notified when data changed
- 11. Example:
- 13. Repositories Repository : Is an observable that supplies data and defines an event as a change of the supplied data. Repositories Types : Simple repositories 1.1 – Static Repository 2.1 - Mutable Repositories 2. Complex repositories
- 14. Static Repository Supply same value and doesn’t generate any events
- 15. Supply value when data changed to any number of Updatables Mutable Repositories
- 16. • Mutable Repository Example
- 17. Repositories 2. Complex repositories : Listen to changes in other repositories and observables and emit these changes to other Updatables, also can apply data stream operators when data change before notify Updatables.
- 18. Compiled repositories Compiled repositories are complex repositories initialized in one expression and contains these parts In this order : 1 - Repositories.repositoryWithInitialValue(...); 2 - Event sources - .observe(...); 3 - Frequency of reaction - .onUpdatesPer(...) or .onUpdatesPerLoop(); 4 - Data processing flow - .getFrom(...), .mergeIn(...), .transform(...), etc.; 5 - Miscellaneous configurations - .notifyIf(...), .onDeactivation(...), etc.; 6 - .compile().
- 20. Data processing flow The data processing flow consists of directives. Each directive accepts an input value and produces an output value for the next directive. The input value type to the first directive is the repository value type, and so is the output value type of the last directive.
- 21. Compiled functions Compiled functions: are the operators used in data flow like apply , map , filter and limit
- 22. Reservoirs and parallelism A Reservoir is the reactive version of a Queue
- 23. Attempts and Result Data flow may produce errors , so we use Result object to get success or fail result from any operator. These functions return Result<T> 1- attemptGetFrom(Supplier).or…; 2- attemptTransform(Function).or…; 3- attemptMergeIn(Supplier, Merger).or…,
- 24. Agera and Retrofit Retrofit : Is a very popular HTTP client for Android Development , and make any http request is very easy and clear. for Integrating Retrofit with Agera with use open source library called Retrofit Agera call adapter
- 25. Agera and Retrofit Retrofit object created as : Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://www.omdbapi.com/") .client(new OkHttpClient()) .addCallAdapterFactory(AgeraCallAdapterFactory.create()) .addConverterFactory(GsonConverterFactory.create()) .build(); final Service service = retrofit.create(Service.class);
- 26. Agera and Retrofit Define API Interface like this interface Service { @GET("1") Supplier<Result<Movie>> android(); @GET("{page}") Supplier<Result<Response<Movie>>> getMovies(@Path("page") int page); }
- 27. Agera and Retrofit then we initialize Repository like this repository = Repositories.repositoryWithInitialValue(INITIAL_VALUE) .observe() .onUpdatesPerLoop() .goTo(networkExecutor) .attemptGetFrom(service.android()) .orSkip() .thenTransform(Result.Success) .compile();
- 28. Agera vs RxJava Agera RxJava Observables 1- Repository 2-MutableRepository 1- Flowable 2- Observable 3- Single 4- Maybe Subscribers 1- Updatable 1- Observer 2- Consumer 3- Subject Operators 1- Function.apply(TFrom) 2- Function.unpack(TFrom) 3- Function.filter(TFrom) 4- Function.map(TFrom) 5- Function.morph(TFrom) 6- Function.limit(TFrom) 7- Merger.merge(TFirst, TSecond) filter,map,flatMap,skip,skipLast, range,firs,tlast,min,max etc... https://github.com/ReactiveX/RxJa va/wiki/Alphabetical-List-of- Observable-Operators
- 29. Resources 1. http://reactivex.io/intro.html 2. http://www.reactivemanifesto.org/ 3. https://github.com/google/agera/ 4. https://github.com/drakeet/retrofit-agera-call-adapter 5. https://medium.freecodecamp.com/rxandroid-and-retrofit-2-0- 66dc52725fff#.p222b0bvj
- 30. Questions ?? No :) Thank You