Skip to main content

​
Introduction

Appsiel Print Manager (APM) is a cross-platform print management system built with .NET MAUI and C#. The system follows a clean, layered architecture pattern with clear separation of concerns between business logic, infrastructure, and presentation layers.

​
Architecture Diagram

​
System Components

The APM system consists of six main components:

​
1. Core Layer

  • Purpose: Domain models and contracts
  • Location: source/Core/
  • Dependencies: None (pure .NET)
  • Key Elements:
    • Interface definitions (IWebSocketService, IPrintService, ITicketRenderer, etc.)
    • Domain models (PrintJobRequest, PrinterSettings, ScaleData, etc.)
    • Enumerations and data contracts

​
2. Infrastructure Layer

  • Purpose: Concrete implementations of core interfaces
  • Location: source/Infraestructure/
  • Dependencies: Core layer only
  • Key Services:
    • WebSocketServerService - WebSocket server implementation
    • PrintService - Print job orchestration
    • TicketRendererService - Template rendering engine
    • EscPosGeneratorService - ESC/POS command generation (thermal printers)
    • EscPGeneratorService - ESC/P command generation (dot matrix printers)
    • SerialScaleService - Serial scale communication
    • Repository implementations for settings and templates

​
3. WorkerService (Windows Service)

  • Purpose: Background print server for Windows
  • Location: source/WorkerService/
  • Platform: Windows only
  • Key Features:
    • Runs as a Windows Service (always-on)
    • Hosts WebSocket server on port 7000
    • Processes print jobs from web clients
    • Manages template updates
    • Validates and ensures default templates exist

​
4. UI Application (.NET MAUI)

  • Purpose: Cross-platform management interface
  • Location: source/UI/
  • Platforms: Windows, Android
  • Key Features:
    • Printer configuration and management
    • Scale configuration and monitoring
    • Template editor
    • System logs viewer
    • Settings management
    • Platform-specific services (Windows: service management, Android: WebSocket client)

​
5. TrayApp (System Tray)

  • Purpose: Windows system tray integration
  • Location: source/TrayApp/
  • Platform: Windows only (WPF)
  • Key Features:
    • System tray icon and menu
    • WorkerService start/stop control
    • Launch UI application
    • Service status monitoring

​
6. ConsoleApp

  • Purpose: Command-line testing and debugging
  • Location: source/ConsoleApp/
  • Platform: All platforms

​
Layered Architecture

APM follows the Clean Architecture pattern with clear dependency rules:

​
Dependency Rules

  1. Core Layer has no dependencies - it defines the contracts
  2. Infrastructure Layer depends only on Core - it implements the contracts
  3. Presentation Layer depends on both Core and Infrastructure
  4. All dependencies point inward toward Core

​
Benefits

  • Testability: Core business logic can be tested independently
  • Maintainability: Changes to infrastructure don’t affect core logic
  • Flexibility: Easy to swap implementations (e.g., different storage providers)
  • Platform Independence: Core layer is platform-agnostic

​
Communication Flow

​
Template Update Flow

​
Scale Data Flow

​
Deployment Models

​
Windows Deployment

┌─────────────────────────────────────┐
│         Windows Machine              │
├─────────────────────────────────────┤
│                                      │
│  ┌──────────────────────────────┐   │
│  │  WorkerService.exe           │   │
│  │  (Windows Service)           │   │
│  │  - WebSocket Server :7000    │   │
│  │  - Auto-start on boot        │   │
│  └──────────────────────────────┘   │
│                                      │
│  ┌──────────────────────────────┐   │
│  │  TrayApp.exe                 │   │
│  │  (System Tray)               │   │
│  │  - Auto-start on login       │   │
│  └──────────────────────────────┘   │
│                                      │
│  ┌──────────────────────────────┐   │
│  │  UI.exe                      │   │
│  │  (.NET MAUI App)             │   │
│  │  - On-demand launch          │   │
│  └──────────────────────────────┘   │
│                                      │
└─────────────────────────────────────┘

​
Android Deployment

┌─────────────────────────────────────┐
│        Android Device                │
├─────────────────────────────────────┤
│                                      │
│  ┌──────────────────────────────┐   │
│  │  APM.apk                     │   │
│  │  (.NET MAUI App)             │   │
│  │  - WebSocket Server          │   │
│  │  - Full UI                   │   │
│  │  - Background service        │   │
│  └──────────────────────────────┘   │
│                                      │
└─────────────────────────────────────┘

​
Data Storage

APM uses JSON-based file storage for configuration:
  • Printer Settings: printers.json - Stores printer configurations
  • Templates: Individual JSON files per document type
  • Dot Matrix Templates: Separate JSON files for matrix printer layouts
  • Scale Configuration: scales.json - Serial scale settings
  • Logs: File-based logging

​
Storage Location

  • Windows: %APPDATA%\AppsielPrintManager\
  • Android: Application-specific storage

​
Technology Stack

  • Framework: .NET 10.0
  • UI Framework: .NET MAUI (Multi-platform App UI)
  • Windows Service: Microsoft.Extensions.Hosting.WindowsServices
  • WebSocket: WatsonWebsocket library
  • Barcode/QR: ZXing.Net with SkiaSharp
  • Image Processing: SkiaSharp
  • Serial Communication: System.IO.Ports
  • DI Container: Microsoft.Extensions.DependencyInjection

​
Security Considerations

  1. Local Network Only: WebSocket server binds to localhost or local network
  2. No Authentication: Designed for trusted local network environments
  3. Service Isolation: Windows Service runs with appropriate permissions
  4. File System Access: Controlled access to configuration directories

​
Next Steps

Build docs developers (and LLMs) love

Get started for freeTalk to us