jarvis

Flutter Enterprise Architecture Documentation

This comprehensive document outlines the architecture for a large-scale Flutter application, adhering to best practices and SOLID principles. It incorporates well-maintained packages from pub.dev to leverage existing solutions, ensuring scalability, maintainability, and efficiency suitable for enterprise-level applications.

Executive Summary
Overview
High-Level Architecture
Folder Structure
Architecture Layers
- Presentation Layer
- Domain Layer
- Data Layer
Networking Layer
Caching Strategies
Theming
Localization
Logging
Error Handling and Reporting
Dependency Injection
Security Best Practices
Accessibility
Performance Optimization
Testing Strategies
Continuous Integration/Continuous Deployment (CI/CD)
Version Control and Branching Strategy
Code Quality Measures
Feedback Mechanisms
Platform-Specific Widgets
Glossary
Conclusion
References

Executive Summary

This document serves as a blueprint for developing a large-scale Flutter application using a clean architecture approach. It emphasizes best practices, SOLID principles, and the use of reliable packages from pub.dev. The architecture is designed to be scalable, maintainable, and testable, suitable for enterprise-level applications. Key components include:

A well-defined folder structure.
Separation of concerns through distinct architecture layers.
Use of state management with flutter_bloc.
Networking with dio and retrofit.
Implementation of caching strategies using hive and shared_preferences.
Theming and localization support.
Logging and error handling with logger and sentry_flutter.
Integration of security best practices and accessibility guidelines.
Comprehensive testing strategies and CI/CD integration.

Overview

The architecture follows the clean architecture paradigm, promoting separation of concerns and scalability. It is divided into three main layers:

Presentation Layer: Handles UI and user interactions.
Domain Layer: Contains business logic and domain models.
Data Layer: Manages data retrieval from network, cache, or local storage.

Utilizing well-maintained packages enhances functionality, expedites development, and ensures adherence to industry standards.

High-Level Architecture

Note: Insert a high-level architecture diagram illustrating the layers and their interactions.

Folder Structure

A well-organized folder structure is crucial for maintainability and scalability.

lib/
├── core/
│   ├── errors/
│   ├── usecases/
│   ├── utils/
│   ├── theme/
│   ├── localization/
│   ├── widgets/
│   └── constants/
├── features/
│   ├── login/
│   │   ├── presentation/
│   │   ├── domain/
│   │   └── data/
│   └── profile/
│       ├── presentation/
│       ├── domain/
│       └── data/
├── services/
│   ├── network/
│   ├── cache/
│   ├── logging/
│   ├── di/
│   ├── analytics/
│   └── security/
├── tests/
│   ├── unit/
│   ├── widget/
│   └── integration/
└── main.dart

core: Contains shared resources used across features.
features: Each feature (e.g., login, profile) is a separate module.
services: Contains networking, caching, logging, dependency injection, analytics, and security services.
tests: Organized tests for unit, widget, and integration testing.

Architecture Layers

Presentation Layer

Packages Used:

flutter_bloc: For state management.
flutter_hooks: For enhanced widget functionality.
flutter_screenutil: For responsive UI.
flutter_platform_widgets: For platform-specific widgets.

Rationale:

flutter_bloc: Preferred for its separation of business logic and UI, and its reactive programming model.
flutter_hooks: Simplifies stateful widgets and enhances code readability.
flutter_screenutil: Ensures UI adapts to different screen sizes.
flutter_platform_widgets: Provides native look and feel on different platforms.

Example: Login Screen

// features/login/presentation/bloc/login_bloc.dart
import 'package:bloc/bloc.dart';
import 'package:equatable/equatable.dart';

class LoginBloc extends Bloc<LoginEvent, LoginState> {
  final AuthenticateUser authenticateUser;

  LoginBloc(this.authenticateUser) : super(LoginInitial());

  @override
  Stream<LoginState> mapEventToState(LoginEvent event) async* {
    // Handle events and yield states
  }
}

// features/login/presentation/pages/login_screen.dart
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:flutter_platform_widgets/flutter_platform_widgets.dart';

class LoginScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocProvider(
      create: (context) => LoginBloc(context.read<AuthenticateUser>()),
      child: Scaffold(
        body: LoginForm(),
      ),
    );
  }
}

Domain Layer

Packages Used:

equatable: For value equality in models.
dartz: For functional programming constructs like Either.

Rationale:

equatable: Simplifies model comparisons.
dartz: Provides robust functional programming patterns.

Example: Authentication Use Case

// features/login/domain/usecases/authenticate_user.dart
class AuthenticateUser {
  final AuthRepository repository;

  AuthenticateUser(this.repository);

  Future<Either<Failure, User>> call(AuthParams params) {
    return repository.authenticate(params);
  }
}

Data Layer

Packages Used:

dio: For HTTP client.
retrofit: For API client generation.
hive: For local storage.
shared_preferences: For key-value storage.
connectivity_plus: For network connectivity checks.

Rationale:

dio: Offers advanced HTTP features and easy integration of interceptors.
retrofit: Simplifies API client creation with annotations.
hive: Lightweight and fast local storage solution.
shared_preferences: For simple key-value storage needs.
connectivity_plus: Provides network connectivity status.

Example: Auth Repository Implementation

// features/login/data/repositories/auth_repository_impl.dart
class AuthRepositoryImpl implements AuthRepository {
  final AuthRemoteDataSource remoteDataSource;
  final AuthLocalDataSource localDataSource;
  final NetworkInfo networkInfo;

  AuthRepositoryImpl({
    required this.remoteDataSource,
    required this.localDataSource,
    required this.networkInfo,
  });

  @override
  Future<Either<Failure, User>> authenticate(AuthParams params) async {
    if (await networkInfo.isConnected) {
      try {
        final user = await remoteDataSource.authenticate(params);
        localDataSource.cacheUser(user);
        return Right(user);
      } on ServerException {
        return Left(ServerFailure());
      }
    } else {
      try {
        final user = await localDataSource.getCachedUser();
        return Right(user);
      } on CacheException {
        return Left(CacheFailure());
      }
    }
  }
}

Networking Layer

Packages Used:

Rationale:

dio: Provides a powerful HTTP client with advanced features.
retrofit: Generates type-safe API clients.
pretty_dio_logger: Enhances logging of network requests.
dio_http_cache: Enables caching of HTTP responses.
connectivity_plus: Checks network status for handling offline scenarios.

Example: Network Client Setup

// services/network/network_client.dart
class NetworkClient {
  final Dio dio;

  NetworkClient() : dio = Dio() {
    dio.options = BaseOptions(
      connectTimeout: 5000,
      receiveTimeout: 3000,
    );
    dio.interceptors.add(PrettyDioLogger());
    dio.interceptors.add(DioCacheManager(CacheConfig()).interceptor);
    dio.interceptors.add(RetryInterceptor());
    dio.interceptors.add(CircuitBreakerInterceptor());
  }
}

Note: Implement RetryInterceptor and CircuitBreakerInterceptor based on application needs.

Caching Strategies

Packages Used:

Rationale:

hive: For structured local data storage with high performance.
shared_preferences: For simple, lightweight key-value storage.
dio_http_cache: For caching network responses transparently.

Example: Cache Data Source

// features/login/data/datasources/auth_local_data_source.dart
class AuthLocalDataSource {
  final HiveInterface hive;

  AuthLocalDataSource({required this.hive});

  Future<void> cacheUser(UserModel user) async {
    final box = await hive.openBox('userBox');
    await box.put('cachedUser', user.toJson());
  }

  Future<UserModel> getCachedUser() async {
    final box = await hive.openBox('userBox');
    final jsonString = box.get('cachedUser');
    if (jsonString != null) {
      return UserModel.fromJson(jsonString);
    } else {
      throw CacheException();
    }
  }
}

Theming

Packages Used:

flutter_screenutil

Rationale:

Ensures consistent UI across different devices and screen sizes.

Example: Theme Configuration

// core/theme/app_theme.dart
class AppTheme {
  static ThemeData lightTheme = ThemeData(
    primaryColor: Colors.blue,
    brightness: Brightness.light,
    textTheme: TextTheme(
      bodyText1: TextStyle(fontSize: 16.sp),
      // Other text styles
    ),
    // Other theme properties
  );

  static ThemeData darkTheme = ThemeData(
    primaryColor: Colors.blueGrey,
    brightness: Brightness.dark,
    textTheme: TextTheme(
      bodyText1: TextStyle(fontSize: 16.sp),
      // Other text styles
    ),
    // Other theme properties
  );
}

Localization

Packages Used:

Rationale:

intl: Official package for internationalization.
intl_utils: Simplifies code generation for localization.

Setup:

Add dependencies:

dependencies:
  flutter_localizations:
    sdk: flutter
  intl: ^0.17.0
dev_dependencies:
  intl_utils: ^2.4.0

Configure pubspec.yaml:

flutter:
  assets:
    - assets/languages/

Create ARB files for each language:
- intl_en.arb
- intl_es.arb
Generate localization files using intl_utils:
```
flutter pub run intl_utils:generate
```

Usage in Code

// main.dart
return MaterialApp(
  localizationsDelegates: [
    GlobalMaterialLocalizations.delegate,
    GlobalWidgetsLocalizations.delegate,
    GlobalCupertinoLocalizations.delegate,
    // Add generated localization delegate
    AppLocalizations.delegate,
  ],
  supportedLocales: [
    Locale('en', ''),
    Locale('es', ''),
    // Other supported locales
  ],
  // ...
);

Logging

Packages Used:

Rationale:

logger: Provides advanced logging features with customizable log levels.
sentry_flutter: Captures and reports errors to an external service.

Example: Logging Service

// services/logging/logging_service.dart
import 'package:logger/logger.dart';
import 'package:sentry_flutter/sentry_flutter.dart';

class LoggingService {
  final Logger _logger = Logger();

  void logDebug(String message) {
    _logger.d(message);
  }

  void logInfo(String message) {
    _logger.i(message);
  }

  void logWarning(String message) {
    _logger.w(message);
  }

  void logError(String message, [dynamic error, StackTrace? stackTrace]) {
    _logger.e(message, error, stackTrace);
    Sentry.captureException(error, stackTrace: stackTrace);
  }
}

Error Handling and Reporting

Packages Used:

Rationale:

dartz: Enables functional error handling using Either types.
sentry_flutter: Handles error reporting effectively, eliminating the need for redundant packages.

Standardized Exception Handling:

Define custom exceptions and failures.
Use Either types to handle errors functionally.
Log errors using LoggingService.

Example: Error Handling in Use Case

// features/login/domain/usecases/authenticate_user.dart
class AuthenticateUser {
  final AuthRepository repository;

  AuthenticateUser(this.repository);

  Future<Either<Failure, User>> call(AuthParams params) async {
    try {
      return await repository.authenticate(params);
    } on ServerException catch (e, stackTrace) {
      LoggingService().logError('ServerException in AuthenticateUser', e, stackTrace);
      return Left(ServerFailure());
    } on CacheException catch (e, stackTrace) {
      LoggingService().logError('CacheException in AuthenticateUser', e, stackTrace);
      return Left(CacheFailure());
    } catch (e, stackTrace) {
      LoggingService().logError('UnknownException in AuthenticateUser', e, stackTrace);
      return Left(UnknownFailure());
    }
  }
}

Dependency Injection

Packages Used:

Rationale:

get_it: Simple and effective service locator.
injectable: Automates dependency injection setup with code generation.

Setup:

Add dependencies:

dependencies:
  get_it: ^7.2.0
  injectable: ^1.5.3
dev_dependencies:
  injectable_generator: ^1.5.3
  build_runner: ^2.1.7

Create an injection configuration:

// services/di/injection.dart
import 'package:get_it/get_it.dart';
import 'package:injectable/injectable.dart';

final getIt = GetIt.instance;

@injectableInit
void configureDependencies() => $initGetIt(getIt);

Annotate classes with @injectable and generate code:

flutter pub run build_runner build --delete-conflicting-outputs

Singletons vs Factories:

Use singletons for services that should have only one instance (e.g., LoggingService).
Use factories for classes that need a new instance each time (e.g., Bloc classes).

Usage in Code

// main.dart
void main() {
  configureDependencies();
  runApp(MyApp());
}

// Accessing dependencies
final authRepository = getIt<AuthRepository>();

Security Best Practices

Packages Used:

flutter_secure_storage: For storing sensitive data securely.
http_interceptor: For adding security headers.

Key Practices:

Secure Storage: Use flutter_secure_storage to store tokens and sensitive information.
Input Validation: Validate all user inputs to prevent injection attacks.
API Security: Implement token-based authentication and refresh mechanisms.
SSL Pinning: Ensure secure communication with the server.

Example: Secure Storage Usage

// services/security/secure_storage_service.dart
import 'package:flutter_secure_storage/flutter_secure_storage.dart';

class SecureStorageService {
  final FlutterSecureStorage _storage = FlutterSecureStorage();

  Future<void> saveToken(String token) async {
    await _storage.write(key: 'auth_token', value: token);
  }

  Future<String?> getToken() async {
    return await _storage.read(key: 'auth_token');
  }
}

Accessibility

Guidelines:

Follow Flutter's accessibility guidelines.
Use semantic widgets and labels.
Ensure proper contrast ratios.

Implementation:

Labels: Use Semantics widget to provide accessibility labels.
Navigation: Ensure focus order is logical.
Testing: Use accessibility tools to test the app.

Example:

// features/login/presentation/widgets/login_button.dart
Semantics(
  label: 'Login Button',
  child: ElevatedButton(
    onPressed: _login,
    child: Text('Login'),
  ),
);

Performance Optimization

Strategies:

Lazy Loading: Load data and widgets only when needed.
Efficient State Management: Use flutter_bloc efficiently to prevent unnecessary rebuilds.
Profiling Tools: Utilize Flutter DevTools for performance monitoring.

Tips:

Avoid rebuilding entire widget trees unnecessarily.
Use const constructors where possible.
Optimize images and assets.

Testing Strategies

Packages Used:

flutter_test: For writing tests.
mockito: For mocking dependencies.
bloc_test: For testing BLoC classes.

Types of Tests:

Unit Tests: Test individual functions and classes.
Widget Tests: Test UI components.
Integration Tests: Test complete app flows.

Continuous Integration:

Integrate testing into CI/CD pipelines to automate test execution.

Example: Unit Test with Mockito

// tests/unit/authenticate_user_test.dart
import 'package:flutter_test/flutter_test.dart';
import 'package:mockito/mockito.dart';

class MockAuthRepository extends Mock implements AuthRepository {}

void main() {
  late AuthenticateUser usecase;
  late MockAuthRepository mockAuthRepository;

  setUp(() {
    mockAuthRepository = MockAuthRepository();
    usecase = AuthenticateUser(mockAuthRepository);
  });

  test('should authenticate user', () async {
    // Arrange
    when(mockAuthRepository.authenticate(any))
        .thenAnswer((_) async => Right(User()));

    // Act
    final result = await usecase(AuthParams(...));

    // Assert
    expect(result, isA<Right>());
    verify(mockAuthRepository.authenticate(any));
    verifyNoMoreInteractions(mockAuthRepository);
  });
}

Continuous Integration/Continuous Deployment (CI/CD)

Tools:

GitHub Actions: For automating builds, tests, and deployments.
Fastlane: For automating app store deployments.

Automated Testing:

Configure pipelines to run tests on each commit.
Use code coverage tools to monitor test effectiveness.

Deployment:

Automate deployment to Google Play Store and Apple App Store.
Use environment variables for managing configurations.

Version Control and Branching Strategy

Git Flow:

Utilize Git Flow for managing branches:
- Master/Main: Production-ready code.
- Develop: Latest development changes.
- Feature Branches: For new features.
- Release Branches: For preparing releases.
- Hotfix Branches: For critical fixes.

Commit Guidelines:

Use clear and descriptive commit messages.
Follow conventional commits format.

Code Quality Measures

Linting:

Use flutter_lints for code analysis.
Enforce lint rules in the CI pipeline.

Formatting:

Use dartfmt or flutter format for consistent code formatting.
Configure IDEs to format on save.

Feedback Mechanisms

Packages Used:

feedback: For in-app user feedback.
firebase_analytics: For user behavior analytics.

Implementation:

Integrate feedback widgets in the app.
Use analytics to gather insights on app usage.

Platform-Specific Widgets

Packages Used:

flutter_platform_widgets

Rationale:

Provides native look and feel on both iOS and Android platforms.

Example: Platform-Specific Button

// features/login/presentation/widgets/platform_button.dart
import 'package:flutter_platform_widgets/flutter_platform_widgets.dart';

class PlatformButton extends StatelessWidget {
  final String text;
  final VoidCallback onPressed;

  PlatformButton({required this.text, required this.onPressed});

  @override
  Widget build(BuildContext context) {
    return PlatformElevatedButton(
      child: Text(text),
      onPressed: onPressed,
      material: (_, __) => MaterialElevatedButtonData(),
      cupertino: (_, __) => CupertinoButtonData(),
    );
  }
}

Glossary

BLoC: Business Logic Component, a design pattern for managing state.
SOLID: Acronym for five design principles intended to make software designs more understandable, flexible, and maintainable.
CI/CD: Continuous Integration/Continuous Deployment, practices that automate the processes of code integration and deployment.
Dartz: A functional programming library for Dart.

Conclusion

This architecture leverages well-established packages and best practices to build a scalable, maintainable Flutter application suitable for enterprise environments. By adhering to SOLID principles and incorporating the outlined strategies, the development team can deliver high-quality features efficiently.

References

Note to Senior Engineers: This document is intended as a comprehensive guide for implementing the application. Adjustments can be made to suit specific project requirements. A sample project implementing this architecture can be found at GitHub Repository.

Next Steps

Set Up Development Environment: Ensure all team members have the necessary tools installed.
Initialize Project Structure: Create the folder structure as outlined.
Configure CI/CD Pipelines: Set up automated builds and tests.
Begin Implementation: Start coding the core features, following the guidelines provided.

By following this architecture and utilizing the recommended packages, the development team can focus on delivering robust, scalable features with confidence in the application's underlying infrastructure.

flutter pub run dart_code_metrics:metrics analyze lib/ flutter test --coverage genhtml coverage/lcov.info -o coverage/html

hkarmoush/jarvis

jarvis

Flutter Enterprise Architecture Documentation

Table of Contents

Executive Summary

Overview

High-Level Architecture

Folder Structure

Architecture Layers

Presentation Layer

Domain Layer

Data Layer

Networking Layer

Caching Strategies

Theming

Localization

Logging

Error Handling and Reporting

Dependency Injection

Security Best Practices

Accessibility

Performance Optimization

Testing Strategies

Continuous Integration/Continuous Deployment (CI/CD)

Version Control and Branching Strategy

Code Quality Measures

Feedback Mechanisms

Platform-Specific Widgets

Glossary

Conclusion

References

Next Steps