Architecture¶

This document provides an overview of the Catalog application architecture for developers.

Technology Stack¶

Frontend¶

Catalog is built using Flutter for cross-platform development:

Framework: Flutter 3.x
Language: Dart
State Management: Provider/Riverpod
HTTP Client: Dio
Local Storage: SharedPreferences, SQLite

Platforms¶

The application targets multiple platforms from a single codebase:

Web: Flutter Web compiled to JavaScript
iOS: Native iOS application
Android: Native Android application
Desktop: Windows, macOS, Linux via Flutter desktop

Project Structure¶

Catalog/
├── lib/
│   ├── main.dart           # Application entry point
│   ├── models/             # Data models
│   ├── services/           # API and business logic
│   ├── providers/          # State management
│   ├── screens/            # UI screens
│   ├── widgets/            # Reusable widgets
│   └── utils/              # Utilities and helpers
├── assets/                 # Static assets (images, fonts)
├── config/                 # Configuration files
├── test/                   # Unit and widget tests
└── docs/                   # Documentation (you are here)

Key Components¶

Services Layer¶

Services handle external communication and business logic:

API Service: HTTP communication with backend services
Auth Service: Authentication and session management
Search Service: Search query handling and result processing
Cache Service: Local caching for offline support

State Management¶

Application state is managed through:

Providers: Dependency injection and state containers
Notifiers: Reactive state updates
Selectors: Computed/derived state

Data Flow¶

User Action → Provider → Service → API
                ↓
            State Update
                ↓
            UI Rebuild

Backend Integration¶

API Communication¶

Catalog communicates with backend services via:

REST APIs for CRUD operations
WebSockets for real-time updates
GraphQL for complex queries (where applicable)

Authentication¶

Authentication flow:

User enters credentials
Auth service validates with backend
JWT token stored securely
Token included in subsequent requests
Token refresh handled automatically

Build & Deployment¶

Build Environments¶

Local: Development builds with debug tools
Development: Deployed to dev environment
QA: Quality assurance testing
Staging: Pre-production verification
Production: Live deployment

CI/CD Pipeline¶

Automated deployment via GitHub Actions:

Code pushed to branch
Build triggered
Tests executed
Docker image created
Deployed to target environment

Configuration¶

Environment Configuration¶

Environment-specific settings in config/:

API endpoints
Feature flags
Logging levels
Analytics configuration

Runtime Configuration¶

Some settings configurable at runtime:

User preferences
Theme settings
Cache policies