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Overview

APM provides comprehensive printer management for thermal and dot-matrix printers. The system supports multiple connection types, automatic configuration, and print job distribution to multiple printers.

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Connection Protocols

TCP/IP

Network printers via raw TCP socket (default port 9100)

USB

Local printers connected via USB using Windows printer names

IPP

Internet Printing Protocol for modern network printers

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Printer Configuration

Each printer is identified by a unique PrinterId and configured with connection and behavior settings.

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PrinterSettings Model

Core/Models/PrinterSettings.cs
public class PrinterSettings
{
    public string PrinterId { get; set; }              // Unique identifier
    public string PrinterType { get; set; }            // "Térmica" or "Matricial"
    public string ConnectionType { get; set; }         // "TCP", "USB", or "IPP"
    
    // TCP/IP Configuration
    public string? IpAddress { get; set; }             // e.g., "192.168.1.100"
    public int Port { get; set; }                      // Default: 9100
    
    // USB Configuration
    public string? LocalPrinterName { get; set; }      // Windows printer name
    
    // IPP Configuration
    public string? Uri { get; set; }                   // e.g., "http://printer:631/ipp"
    
    // Paper Settings
    public int PaperWidthMm { get; set; }              // 58mm or 80mm
    
    // Behavior Settings
    public bool BeepOnPrint { get; set; }
    public bool OpenCashDrawerAfterPrint { get; set; }
    public bool OpenCashDrawerWithoutPrint { get; set; }
    
    // Multi-Printer Support
    public List<string> CopyToPrinterIds { get; set; } // Copy to additional printers
}

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Service Interface

The IPrintService interface defines the core printer management operations.

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Configuration Operations

Core/Interfaces/IPrintService.cs
public interface IPrintService
{
    // Configure or update printer settings
    Task ConfigurePrinterAsync(PrinterSettings settings);
    
    // Retrieve settings for a specific printer
    Task<PrinterSettings> GetPrinterSettingsAsync(string printerId);
    
    // Get all configured printers
    Task<List<PrinterSettings>> GetAllPrinterSettingsAsync();
    
    // Remove printer configuration
    Task DeletePrinterSettingsAsync(string printerId);
}

// Process complete print job (parse, render, generate ESC/POS, send)
Task<PrintJobResult> ProcessPrintJobAsync(PrintJobRequest request);
The ProcessPrintJobAsync method orchestrates the entire print workflow: template rendering, ESC/POS command generation, and transmission to the printer(s).
The service implements a complete printing pipeline:
1

Validate Printer

Retrieve printer configuration using PrinterId from the settings repository.
2

Deserialize Document

Convert JSON document data to strongly-typed models based on DocumentType.
3

Select Renderer

Choose thermal (ESC/POS) or dot-matrix (ESC/P) renderer based on template availability.
4

Generate Commands

Convert rendered content to printer-specific command sequences.
5

Send to Primary Printer

Transmit commands to main printer via configured connection type.
6

Send to Copy Printers

If CopyToPrinterIds is configured, send to additional printers.

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Connection Type Selection

The service automatically selects the appropriate client based on configuration:
Infraestructure/Services/PrintService.cs:138-151
// C. Enviar según el tipo de conexión
bool success = false;
if (printerSettings.ConnectionType == "USB" && !string.IsNullOrEmpty(printerSettings.LocalPrinterName))
{
    success = await _localRawPrinterClient.SendRawDataAsync(
        printerSettings.LocalPrinterName, 
        escPCommands, 
        $"APM_{request.JobId}"
    );
}
else if (printerSettings.ConnectionType == "IPP" && !string.IsNullOrEmpty(printerSettings.Uri))
{
    success = await _ippPrinterClient.PrintAsync(printerSettings.Uri, escPCommands);
}
else
{
    // Fallback to TCP for thermal printers
    success = await _tcpIpPrinterClient.PrintAsync(
        printerSettings.IpAddress ?? string.Empty, 
        printerSettings.Port, 
        escPosCommands
    );
}

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Multi-Printer Copy Distribution

APM supports automatic job distribution to multiple printers using the CopyToPrinterIds property:
Infraestructure/Services/PrintService.cs:176-198
if (printerSettings.CopyToPrinterIds != null && printerSettings.CopyToPrinterIds.Any())
{
    foreach (var copyPrinterId in printerSettings.CopyToPrinterIds)
    {
        var copyPrinterSettings = await _settingsRepository.GetPrinterSettingsAsync(copyPrinterId);
        if (copyPrinterSettings == null)
        {
            _logger.LogWarning($"Impresora de copia con ID '{copyPrinterId}' no encontrada.");
            continue;
        }
        
        _logger.LogInfo($"Enviando copia a impresora '{copyPrinterId}'.");
        var copyEscPosCommands = await _escPosGenerator.GenerateEscPosCommandsAsync(
            ticketContent, 
            copyPrinterSettings
        );
        
        bool copyPrintSuccess = await _tcpIpPrinterClient.PrintAsync(
            copyPrinterSettings.IpAddress ?? string.Empty, 
            copyPrinterSettings.Port, 
            copyEscPosCommands
        );
        
        if (!copyPrintSuccess)
        {
            _logger.LogError($"Fallo al imprimir en impresora de copia '{copyPrinterId}'.");
            // Process continues even if copy fails
        }
    }
}
Copy printer failures do not halt the main print job. The service logs errors but continues processing.

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Supported Document Types

The print service supports multiple document types with specific data models:
  • ticket_venta - Sales receipts
  • comanda - Kitchen/bar order tickets
  • factura_electronica - Electronic invoices
  • sticker_codigo_barras - Barcode labels
  • comprobante_egreso - Expense vouchers
Each document type is deserialized to its corresponding strongly-typed model before rendering.

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Configuration Example

{
  "PrinterId": "thermal_kitchen",
  "PrinterType": "Térmica",
  "ConnectionType": "TCP",
  "IpAddress": "192.168.1.100",
  "Port": 9100,
  "PaperWidthMm": 80,
  "BeepOnPrint": true,
  "OpenCashDrawerAfterPrint": false,
  "CopyToPrinterIds": ["thermal_counter"]
}

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Error Handling

The service provides comprehensive error reporting through PrintJobResult: 
public class PrintJobResult
{
    public string JobId { get; set; }
    public string Status { get; set; }       // "DONE" or "ERROR"
    public string? ErrorMessage { get; set; } // Detailed error description
}

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Next Steps

Template System

Learn how to create custom print templates

WebSocket Server

Integrate with web applications

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