DivisiBillWsClient

A .NET MAUI cross-platform client application for interacting with the DivisiBill Web Service. This mobile/desktop application provides a comprehensive user interface for managing file storage, billing, items, and table data through a web-based API.

Overview

DivisiBillWsClient is built with Microsoft .NET MAUI (Multi-platform App UI) and targets both Android and Windows platforms. It enables users to connect to a DivisiBill Web Service instance and perform operations including file management, billing operations, inventory tracking, and database table operations. It also permits a connection to Azure Data storage to directly access and manage stored items.

Project Structure

Core Application Files

• App.xaml / App.xaml.cs - Application entry point and initialization

  • Configures the main application window (800x800)
  • Stores global settings including the user API key
  • Manages application-level state through SettingsClass

• AppShell.xaml / AppShell.xaml.cs - Shell navigation container

  • Defines the tab-based navigation structure
  • Routes between different pages
  • Displays dynamic title bar

• MauiProgram.cs - MAUI configuration

  • Initializes the MAUI app with platform-specific configurations
  • Registers MAUI Community Toolkit services
  • Configures custom fonts (OpenSans)

Views

The application uses a tabbed interface with five main pages:

1. CallStatusPage (Views/CallStatusPage.xaml)

• Purpose: Basic Web Service configuration and connection testing
• Features:
  • Base URL picker with predefined options or custom URL entry
  • Web service version and status checking
  • Cloud authentication setup (password management)
  • Response display for API calls
• ViewModel: MainPageViewModel

2. FileActivitiesPage (Views/FileActivitiesPage.xaml)

• Purpose: File upload, download, and activity tracking
• Features:
  • View file activity history
  • Manage remote file operations
• ViewModel: MainPageViewModel

3. StoredItemsPage (Views/StoredItemsPage.xaml)

• Purpose: Inventory and stored items management
• Features:
  • Browse stored items on the server
  • Track item metadata
• ViewModel: MainPageViewModel

4. BillingPage (Views/BillingPage.xaml)

• Purpose: Billing and in-app purchase management
• Features:
  • View billing information
  • Manage subscriptions and purchases
• ViewModel: BillingPageViewModel

5. TablePage (Views/TablePage.xaml)

• Purpose: Database table operations
• Features:
  • Access remote database tables
  • View and manage table data
• ViewModel: TablePageViewModel

Additional Views

• ChangePasswordPopup (Views/ChangePasswordPopup.xaml) - Modal popup for password management
  • Used by the Call Status page for cloud authentication setup
  • ViewModel: ChangePasswordViewModel

ViewModels (MVVM Pattern)

All ViewModels inherit from ObservableObject and use the MVVM Toolkit for property change notifications and command binding.

• MainPageViewModel.cs (918 lines)

  • Central view model handling most application logic, it should really be 3 view models, one each for the 3 main pages, but for now it is all in one.
  • Manages web service communication via shared HttpClient
  • Properties:
    • BaseUrl / BaseUrlText - Web service endpoint configuration
    • BaseUrlChoices - Pre-configured service URLs
    • StatusResponse - Display responses from API calls
    • HasPassword - Cloud authentication state
  • Commands:
    • CallVersionCommand - Fetch service version
    • CallStatusCommand - Check service status
    • ChangePasswordCommand - Update user password
    • ClearStatusResponseCommand - Clear response display
  • Methods:
    • OnLoadedAsync() - Page initialization
    • File operations (upload, download, delete)
    • Remote item management

• BillingPageViewModel.cs

  • Handles billing-related operations and in-app purchases
  • Manages purchase validation and subscription state

• ChangePasswordViewModel.cs

  • Manages password change dialog logic
  • Validates and commits password changes

• TablePageViewModel.cs

  • Manages database table operations
  • Handles table data retrieval and updates

Services

• CallWs.cs - Web service communication layer

  • Handles HTTP requests to the DivisiBill Web Service
  • Provides methods for API operations

• CryptManager.cs - Cryptographic operations

  • Manages encryption/decryption for sensitive data
  • Password hashing and verification

• Billing.cs - Billing service integration

  • Manages in-app purchase operations
  • Handles subscription state

• Utilities.cs - Helper utilities

  • Common utility functions used across the application

• CrossInAppBilling.shared.cs - Cross-platform billing abstraction

  • Provides platform-agnostic in-app billing interface

Models

• BillingItem.cs - Data model for billing information

  • Represents a billable item or invoice

• PriceItem.cs - Data model for pricing

  • Represents pricing information

• AndroidPurchase.cs - Android-specific purchase model

  • Handles Android in-app purchase details

Converters

• EnvironmentToStringConverter.cs - XAML value converter
  • Converts environment variables or state objects to display strings
  • Used in bindings for conditional UI display

Resources

• AppIcon - Application branding assets
• Splash - Splash screen displayed on startup
• Images - UI graphics and images
• Fonts - Custom fonts (OpenSans-Regular.ttf)
• Styles - XAML style definitions

Platforms

Platform-specific code for Android and Windows implementations:

• Android-specific manifest configurations
• Windows-specific package definitions

UI Architecture

Navigation Structure

AppShell (TabBar)
├── Status Tab
│   └── CallStatusPage
├── Files Tab
│   └── FileActivitiesPage
├── Items Tab
│   └── StoredItemsPage
├── Billing Tab
│   └── BillingPage
└── Tables Tab
    └── TablePage

Data Flow

The application uses the MVVM pattern with unidirectional data flow:

View (XAML)
    ↓
Data Binding
    ↓
ViewModel (ObservableObject with Commands)
    ↓
Services (HttpClient, CryptManager, etc.)
    ↓
Web Service / Local Storage

Key Features

Web Service Integration

• Configurable Base URL - Connect to different DivisiBill instances
• API Key Management - Store and manage authentication credentials
• HTTP Client Pooling - Shared HttpClient for efficient resource usage
• Version Checking - Verify service availability and version

Authentication

• Password Management - Set or change cloud authentication passwords
• Secure Credential Storage - Uses encryption for sensitive data
• API Key Support - Environment-based key configuration for multiple deployments

File Management

• File upload and download capabilities
• Activity tracking for file operations
• Remote file deletion

Billing & In-App Purchases

• Android in-app purchase integration
• Subscription management
• Purchase validation and history

Platform-Specific Features

• Android: Native purchase implementation, device integration
• Windows: Desktop application with touch/keyboard input support

Configuration

Base URL Configuration

The application provides multiple ways to configure the web service URL:

1. Built-in Production URL - From Generated.BuildInfo.DivisiBillWsUri
2. Environment Variables:
   • DIVISIBILL_WS_URI_RELEASE - Production deployment
   • DIVISIBILL_ALTERNATE_WS_URI - Alternate service instance
3. Manual Entry - Users can enter custom URLs via the UI

API Key Management

API keys are automatically selected based on the configured base URL:

• Production URL uses production key from build info
• Environment variable URLs use corresponding environment keys
• Manual URLs require users to provide credentials

Building and Deployment

Target Frameworks

• net10.0-android - Android application
• net10.0-windows10.0.19041.0 - Windows desktop application (when building on Windows)

Build Configuration

• Language Version: Preview (Latest C# features)
• Nullable Reference Types: Enabled
• XAML Compilation: With source compilation binding support
• Unsafe Blocks: Enabled for interop scenarios
• Material Design 3: Enabled for modern UI styling

Application Metadata

• Display Name: DivisiBillWsClient
• Package ID: com.autoplus.divisibill
• Version: 1.0

Dependencies

Primary Frameworks

• .NET MAUI (Microsoft.Maui.*)
• MVVM Community Toolkit (CommunityToolkit.Mvvm)
• MAUI Community Toolkit (CommunityToolkit.Maui)

Features

• HTTP/JSON communication (.NET System.Net.Http.Json)
• Cryptography (.NET System.Security.Cryptography)
• File operations and storage access
• In-app billing integration

Development Notes

MVVM Implementation

• Uses ObservableObject base class for automatic property change notifications
• Implements IRelayCommand for command binding
• Supports property change notifications with [NotifyPropertyChangedFor] attributes

Cross-Platform Considerations

• Platform-specific code in Platforms/ directory
• Conditional compilation for Android/Windows differences
• Abstract services for cross-platform functionality

Settings Persistence

• SettingsClass in App.cs maintains application settings
• UserKey property stores API credentials
• Settings persist across application sessions

Security Considerations

• Credentials stored in SettingsClass should be treated as sensitive
• API keys should be protected in configuration/environment variables
• HTTPS is recommended for all web service communication
• Cryptographic operations use standard .NET cryptography APIs

Extensibility

The architecture supports easy addition of new features:

1. New Pages: Add XAML page + code-behind + ViewModel
2. New Services: Add service class with dependency injection
3. New Models: Add data model class in Models/
4. Platform Features: Add platform-specific code in Platforms/

License

Refer to the root repository LICENSE.txt file.