适用于 WinForms、WPF 和 Avalonia 的 C# & VB 日志查看器控件

public interface ILogDataStore
{
    ObservableCollection<LogModel> Entries { get; }
    void AddEntry(LogModel logModel);
}

public class LogDataStore : ILogDataStore
{
    #region Fields

    private static readonly SemaphoreSlim _semaphore = new(initialCount: 1);

    #endregion

    #region Properties

    public ObservableCollection<LogModel> Entries { get; } = new();

    #endregion

    #region Methods

    public virtual void AddEntry(LogModel logModel)
    {
        // ensure only one operation at time from multiple threads
        _semaphore.Wait();

        Entries.Add(logModel);

        _semaphore.Release();
    }

    #endregion
}

Public Interface ILogDataStore

  ReadOnly Property Entries As ObservableCollection(Of LogModel)

  Sub AddEntry(logModel As LogModel)

End Interface

Public Class LogDataStore : Implements ILogDataStore

#Region "Fields"

  Private Shared ReadOnly _semaphore = New SemaphoreSlim(initialCount:=1)

#End Region

#Region "Properties"

  Public ReadOnly Property Entries As ObservableCollection(Of LogModel) _
    = New ObservableCollection(Of LogModel) _
    Implements ILogDataStore.Entries

#End Region

#Region "Methods"

  Public Overridable Sub AddEntry(logModel As LogModel) _
         Implements ILogDataStore.AddEntry

    ' ensure only one operation at time from multiple threads
    _semaphore.Wait()

    Entries.Add(logModel)

    _semaphore.Release()

  End Sub

#End Region

End Class

public class LogModel
{
    #region Properties

    public DateTime Timestamp { get; set; }

    public LogLevel LogLevel { get; set; }

    public EventId EventId { get; set; }

    public object? State { get; set; }

    public string? Exception { get; set; }

    public LogEntryColor? Color { get; set; }

    #endregion
}

Public Class LogModel

#Region "Properties"

    Public Property Timestamp As Date

    Public Property LogLevel As LogLevel

    Public Property EventId As EventId

    Public Property State As Object

    Public Property Exception As String

    Public Property Color As LogEntryColor

#End Region

End Class

public class DataStoreLoggerConfiguration
{
    #region Properties
    
    public EventId EventId { get; set; }

    public Dictionary<LogLevel, LogEntryColor> Colors { get; } = new()
    {
        [LogLevel.Trace] = new() { Foreground = Color.DarkGray },
        [LogLevel.Debug] = new() { Foreground = Color.Gray },
        [LogLevel.Information] = new(),
        [LogLevel.Warning] = new() { Foreground = Color.Orange},
        [LogLevel.Error] = new() 
        { Foreground = Color.White, Background = Color.OrangeRed },
        [LogLevel.Critical] = new() 
        { Foreground=Color.White, Background = Color.Red },
        [LogLevel.None] = new(),
    };

    #endregion
}

Public Class DataStoreLoggerConfiguration

#Region "Properties"

    Public Property EventId As EventId

    Public Property Colors As Dictionary(Of LogLevel, LogEntryColor) = _
        New Dictionary(Of LogLevel, LogEntryColor) From
    {
        {LogLevel.Trace, New LogEntryColor() With {.Foreground = Color.DarkGray}},
        {LogLevel.Debug, New LogEntryColor() With {.Foreground = Color.Gray}},
        {LogLevel.Information, New LogEntryColor()},
        {LogLevel.Warning, New LogEntryColor() With {.Foreground = Color.Orange}},
        {LogLevel.Error, New LogEntryColor() With _
          {.Foreground = Color.White, .Background = Color.OrangeRed}},
        {LogLevel.Critical, New LogEntryColor() With _
          {.Foreground = Color.White, .Background = Color.Red}},
        {LogLevel.None, New LogEntryColor()}
    }

#End Region

End Class

public class LogEntryColor
{
    public Color Foreground { get; set; } = Color.Black;
    public Color Background { get; set; } = Color.Transparent;
}

Public Class LogEntryColor

    Property Foreground As Color = Color.Black

    Property Background As Color = Color.Transparent

End Class

public class DataStoreLogger: ILogger
{
    #region Constructor

    public DataStoreLogger(
        string name,
        Func<DataStoreLoggerConfiguration> getCurrentConfig,
        ILogDataStore dataStore)
    {
        (_name, _getCurrentConfig) = (name, getCurrentConfig);
        _dataStore = dataStore;
    }

    #endregion

    #region Fields

    private readonly ILogDataStore _dataStore;
    private readonly string _name;
    private readonly Func<DataStoreLoggerConfiguration> _getCurrentConfig;

    #endregion

    #region methods

    public IDisposable BeginScope<TState>(TState state)  
                       where TState : notnull => default!;

    public bool IsEnabled(LogLevel logLevel) => true;

    public void Log<TState>(
        LogLevel logLevel,
        EventId eventId,
        TState state,
        Exception? exception,
        Func<TState, Exception, string> formatter)
    {
        // check if we are logging for passed log level
        if (!IsEnabled(logLevel))
            return;

        DataStoreLoggerConfiguration config = _getCurrentConfig();

        _dataStore.AddEntry(new()
        {
            Timestamp = DateTime.UtcNow,
            LogLevel = logLevel,
            // do we override the default EventId if it exists?
            EventId = eventId.Id == 0 && config.EventId != 0 ? 
                      config.EventId : eventId,
            State = state,
            Exception = exception?.Message ?? 
                (logLevel == LogLevel.Error ? state?.ToString() ?? "" : ""),
            Color = config.Colors[logLevel],
        });
        
        Debug.WriteLine(
          $"--- [{logLevel.ToString()[..3]}] 
          {_name} - {formatter(state, exception!)}");
    }

    #endregion
}

Public Class DataStoreLogger : Implements ILogger

#Region "Constructors"

  Public Sub New(name As String, getCurrentConfig _
  As Func(Of DataStoreLoggerConfiguration), dataStore As ILogDataStore)
    _name = name
    _getCurrentConfig = getCurrentConfig
    _dataStore = dataStore
  End Sub

#End Region

#Region "Fields"

  Private ReadOnly _dataStore As ILogDataStore
  Private ReadOnly _name As String
  Private ReadOnly _getCurrentConfig As Func(Of DataStoreLoggerConfiguration)

#End Region

#Region "Methods"

  Public Function BeginScope(Of TState)(state As TState) As IDisposable
      Implements ILogger.BeginScope
    Return Nothing
  End Function

  Public Function IsEnabled(logLevel As LogLevel) As Boolean
      Implements ILogger.IsEnabled
    Return True
  End Function

  Public Overridable Sub Log(Of TState)(
      logLevel As LogLevel, eventId As EventId,
      state As TState, exception As Exception,
      formatter As Func(Of TState, Exception, String))
      Implements ILogger.Log

    If Not IsEnabled(logLevel) Then
      Return
    End If

    Dim exMessage As String = String.Empty

    If exception IsNot Nothing Then
      If String.IsNullOrEmpty(exception.Message) Then
        If logLevel = LogLevel.Error AndAlso state IsNot Nothing Then
          exMessage = state.ToString()
        End If
      Else
        exMessage = exception.Message
      End If
    End If

    Dim internalEventId As EventId = eventId
    Dim config As DataStoreLoggerConfiguration = _getCurrentConfig()

    If eventId.Id = 0 AndAlso config.EventId.Id <> 0 Then
      internalEventId = config.EventId
    End If

    _dataStore.AddEntry(New LogModel() With
    {
      .Timestamp = Now,
      .LogLevel = logLevel,
      .EventId = internalEventId,
      .State = state,
      .Exception = exMessage,
      .Color = config.Colors(logLevel)
    })

    Debug.WriteLine(
      $"--- [{logLevel.ToString()(0.3)}] {_name} - {formatter(state, exception)}")

  End Sub

#End Region

End Class

public class DataStoreLoggerProvider: ILoggerProvider
{
    #region Constructor
    
    public DataStoreLoggerProvider(
        IOptionsMonitor<DataStoreLoggerConfiguration> config,
        ILogDataStore dataStore)
    {
        _dataStore = dataStore;
        _currentConfig = config.CurrentValue;
        _onChangeToken = config.OnChange(
            updatedConfig => _currentConfig = updatedConfig);
    }

    #endregion

    #region fields
    
    private DataStoreLoggerConfiguration _currentConfig;

    private readonly IDisposable? _onChangeToken;
    protected readonly ILogDataStore _dataStore;

    protected readonly ConcurrentDictionary<string, DataStoreLogger> _loggers = new();
    
    #endregion

    #region Methods
    
    public ILogger CreateLogger(string categoryName)
        => _loggers.GetOrAdd(categoryName, name
            => new DataStoreLogger(name, GetCurrentConfig, _dataStore));

    protected DataStoreLoggerConfiguration GetCurrentConfig()
        => _currentConfig;

    public void Dispose()
    {
        _loggers.Clear();
        _onChangeToken?.Dispose();
    } 

    #endregion
}

Public Class DataStoreLoggerProvider : Implements ILoggerProvider

#Region "Constructors"

  Public Sub New(config As IOptionsMonitor(Of DataStoreLoggerConfiguration),
                 dataStore As ILogDataStore)

    _dataStore = dataStore
    _currentConfig = config.CurrentValue
    _onChangeToken = config.OnChange(Sub(updatedConfig) _currentConfig = updatedConfig)

  End Sub

#End Region

#Region "Fields"

  Private _currentConfig As DataStoreLoggerConfiguration

  Private ReadOnly _onChangeToken As IDisposable
  Protected ReadOnly _dataStore As ILogDataStore

  Protected ReadOnly _loggers As ConcurrentDictionary(Of String, DataStoreLogger) =
            New ConcurrentDictionary(Of String, DataStoreLogger)()

#End Region

#Region "Methods"

  Public Overridable Function CreateLogger(categoryName As String) As ILogger
    Implements ILoggerProvider.CreateLogger

    Return _loggers.GetOrAdd(categoryName,
      Function(name)
        New DataStoreLogger(name, AddressOf GetCurrentConfig, _dataStore)
      End Function)

  End Function

  Protected Function GetCurrentConfig() As DataStoreLoggerConfiguration

    Return _currentConfig

  End Function

  Public Sub Dispose() Implements IDisposable.Dispose

    _loggers.Clear()
    _onChangeToken?.Dispose()

  End Sub

#End Region

End Class

public static class ServicesExtension
{
    public static ILoggingBuilder AddDefaultDataStoreLogger(this ILoggingBuilder builder)
    {
        builder.Services.TryAddEnumerable(
            ServiceDescriptor.Singleton<ILoggerProvider, DataStoreLoggerProvider>());
        return builder;
    }

    public static ILoggingBuilder AddDefaultDataStoreLogger(
        this ILoggingBuilder builder,
        Action<DataStoreLoggerConfiguration> configure)
    {
        builder.AddDefaultDataStoreLogger();
        builder.Services.Configure(configure);
        return builder;
    }
}

Public Module ServicesExtension

  <Extension>
  Public Function AddDefaultDataStoreLogger(builder As ILoggingBuilder) _
         As ILoggingBuilder

    builder.Services.TryAddEnumerable(
      ServiceDescriptor.Singleton(Of ILoggerProvider, DataStoreLoggerProvider))
    Return builder

  End Function

  <Extension>
  Public Function AddDefaultDataStoreLogger( _
    builder As ILoggingBuilder,
    configure As Action(Of DataStoreLoggerConfiguration)) As ILoggingBuilder

    builder.AddDefaultDataStoreLogger()
    builder.Services.Configure(configure)
    Return builder

  End Function

End Module

HostApplicationBuilder builder = Host.CreateApplicationBuilder();

builder.AddLogViewer();
builder.Logging.AddDefaultDataStoreLogger();

_host = builder.Build();

Dim builder As HostApplicationBuilder = Host.CreateApplicationBuilder()

builder.AddLogViewer()
builder.Logging.AddDefaultDataStoreLogger()

_host = builder.Build()

HostApplicationBuilder builder = Host.CreateApplicationBuilder();

builder.AddLogViewer();
builder.Logging.AddDefaultDataStoreLogger(options =>
{
    options.Colors[LogLevel.Trace] = new()
    {
        Foreground = Color.White,
        Background = Color.DarkGray
    };
    options.Colors[LogLevel.Debug] = new()
    {
        Foreground = Color.White,
        Background = Color.Gray
    };
    options.Colors[LogLevel.Information] = new()
    {
        Foreground = Color.White,
        Background = Color.DodgerBlue
    };
    options.Colors[LogLevel.Warning] = new()
    {
        Foreground = Color.White,
        Background = Color.Orchid
    };
});

_host = builder.Build();

Dim builder As HostApplicationBuilder = Host.CreateApplicationBuilder()

builder.AddLogViewer()
builder.Logging.AddDefaultDataStoreLogger(
  Sub(options)

    options.Colors(LogLevel.Trace) = New LogEntryColor() With
    {
      .Foreground = Color.White,
      .Background = Color.DarkGray
    }

    options.Colors(LogLevel.Debug) = New LogEntryColor() With
    {
      .Foreground = Color.White,
      .Background = Color.Gray
    }

    options.Colors(LogLevel.Information) = New LogEntryColor() With
    {
      .Foreground = Color.White,
      .Background = Color.DodgerBlue
    }

    options.Colors(LogLevel.Warning) = New LogEntryColor() With
    {
      .Foreground = Color.White,
      .Background = Color.Orchid
    }

  End Sub)


_host = builder.Build()

public class RandomLoggingService : BackgroundService
{
    #region Constructors

    public RandomLoggingService(ILogger<RandomLoggingService> logger)
        => _logger = logger;

    #endregion

    #region Fields

    private readonly ILogger _logger;

    #endregion
}

Public Class RandomLoggingService : Inherits BackgroundService

#Region "Constructors"

  Public Sub New(logger As ILogger(Of RandomLoggingService))

    _logger = logger

  End Sub

#End Region

#Region "Fields"

  Private _logger As ILogger

#End Region

End Class

ILogger<class_name> logger
  = _host.Services.GetRequiredService<ILogger<class_name>>();

Dim logger As ILogger(Of class_name)
  = _host.Services.GetRequiredService(Of ILogger(Of class_name))

public static class LoggingHelper
{
     #region Constructors

   static LoggingHelper()
    {
        // retrieve the log level from 'appsettings'
        string value = AppSettings<string>.Current("Logging:LogLevel", "Default")
                       ?? "Information";
        Enum.TryParse(value, out LogLevel logLevel);

        // wire up the loggers
        Factory = LoggerFactory.Create(builder => builder

            // visual debugging tools
            .AddDataStoreLogger()

            // examples of adding other loggers...
            .AddSimpleConsole(options =>
            {
                options.SingleLine = true;
                options.TimestampFormat = "hh:mm:ss ";
            })

            // set minimum log level from 'appsettings'
            .SetMinimumLevel(logLevel));
    }

    #endregion

    #region Properties

    public static ILoggerFactory Factory { get; }

    #endregion
}

Public Module LoggingHelper

#Region "Constructors"

 Sub New()

  ' retrieve the log level from 'appsettings'
  Dim value As String = AppSettings(Of String).Current("Logging:LogLevel", "Default")
  If String.IsNullOrWhiteSpace(value) Then
   value = "Information"
  End If

  Dim logLevel As LogLevel
  If Not [Enum].TryParse(value, logLevel) Then
   logLevel = LogLevel.Information
  End If

  ' wire up the loggers
  Factory = LoggerFactory.Create(
   Sub(builder)

    ' visual debugging tools
    builder.AddDataStoreLogger()

    ' example of adding other loggers...
    builder.AddSimpleConsole(
      Sub(options)
       options.SingleLine = True
       options.TimestampFormat = "hh:mm:ss "
      End Sub)

    ' set minimum log level from 'appsettings'
    builder.SetMinimumLevel(logLevel)

   End Sub)

 End Sub

#End Region

#Region "Properties"

 Public ReadOnly Property Factory As ILoggerFactory

#End Region

End Module

public static class LoggingHelper
{
    #region Constructors

    static LoggingHelper()
    {
        // retrieve the log level from 'appsettings'
        string value = AppSettings<string>.Current("Logging:LogLevel", "Default")
                       ?? "Information";
        Enum.TryParse(value, out LogLevel logLevel);

        // wire up the loggers
        Factory = LoggerFactory.Create(builder => builder

            // visual debugging tools
            .AddDataStoreLogger(options =>
            {
                options.Colors[LogLevel.Trace] = new()
                {
                    Foreground = Color.White,
                    Background = Color.DarkGray
                };

                options.Colors[LogLevel.Debug] = new()
                {
                    Foreground = Color.White,
                    Background = Color.Gray
                };

                options.Colors[LogLevel.Information] = new()
                {
                    Foreground = Color.White,
                    Background = Color.DodgerBlue
                };

                options.Colors[LogLevel.Warning] = new()
                {
                    Foreground = Color.White,
                    Background = Color.Orchid
                };
            })

            // examples of adding other loggers...
            .AddSimpleConsole(options =>
            {
                options.SingleLine = true;
                options.TimestampFormat = "hh:mm:ss ";
            })

            // set minimum log level from 'appsettings'
            .SetMinimumLevel(logLevel));
    }

    #endregion

    #region Properties

    public static ILoggerFactory Factory { get; }

    #endregion
}

Public Module LoggingHelper

#Region "Constructors"

 Sub New()

  ' retrieve the log level from 'appsettings'
  Dim value As String = AppSettings(Of String).Current("Logging:LogLevel", "Default")
  If String.IsNullOrWhiteSpace(value) Then
   value = "Information"
  End If

  Dim logLevel As LogLevel
  If Not [Enum].TryParse(value, logLevel) Then
   logLevel = LogLevel.Information
  End If

  ' wire up the loggers
  Factory = LoggerFactory.Create(
   Sub(builder)

    ' visual debugging tools
    builder.AddDataStoreLogger(
      Sub(options)

        options.Colors(LogLevel.Trace) = New LogEntryColor() With
        {
          .Foreground = Color.White,
          .Background = Color.DarkGray
        }

        options.Colors(LogLevel.Debug) = New LogEntryColor() With
        {
          .Foreground = Color.White,
          .Background = Color.Gray
        }

        options.Colors(LogLevel.Information) = New LogEntryColor() With
        {
          .Foreground = Color.White,
          .Background = Color.DodgerBlue
        }

        options.Colors(LogLevel.Warning) = New LogEntryColor() With
        {
          .Foreground = Color.White,
          .Background = Color.Orchid
        }

      End Sub)

    ' example of adding other loggers...
    builder.AddSimpleConsole(
      Sub(options)
       options.SingleLine = True
       options.TimestampFormat = "hh:mm:ss "
      End Sub)

    ' set minimum log level from 'appsettings'
    builder.SetMinimumLevel(logLevel)

   End Sub)

 End Sub

#End Region

#Region "Properties"

 Public ReadOnly Property Factory As ILoggerFactory

#End Region

End Module

Logger<class_name> logger
  = new Logger<class_name>(LoggingHelper.Factory);

Dim logger As Logger(Of class_name)
  = New Logger(Of class_name)(LoggingHelper.Factory)

RandomLoggingService service
  = new(new Logger<RandomLoggingService>(LoggingHelper.Factory));

Dim service As RandomLoggingService
  = New RandomLoggingService(New Logger(Of RandomLoggingService)(LoggingHelper.Factory))

public class DataStoreLoggerSink : ILogEventSink
{
    protected readonly Func<ILogDataStore> _dataStoreProvider;
    
    private readonly IFormatProvider? _formatProvider;
    private readonly Func<DataStoreLoggerConfiguration>? _getCurrentConfig;

    public DataStoreLoggerSink(Func<ILogDataStore> dataStoreProvider,
                               Func<DataStoreLoggerConfiguration>? 
                               getCurrentConfig = null,
                               IFormatProvider? formatProvider = null)
    {
        _formatProvider = formatProvider;
        _dataStoreProvider = dataStoreProvider;
        _getCurrentConfig = getCurrentConfig;
    }

    public void Emit(LogEvent logEvent)
    {
        LogLevel logLevel = logEvent.Level switch
        {
            LogEventLevel.Verbose => LogLevel.Trace,
            LogEventLevel.Debug => LogLevel.Debug,
            LogEventLevel.Warning => LogLevel.Warning,
            LogEventLevel.Error => LogLevel.Error,
            LogEventLevel.Fatal => LogLevel.Critical,
            _ => LogLevel.Information
        };

        DataStoreLoggerConfiguration config =
             _getCurrentConfig?.Invoke() ?? new DataStoreLoggerConfiguration();

        EventId eventId = EventIdFactory(logEvent);
        if (eventId.Id == 0 && config.EventId != 0)
            eventId = config.EventId;

        string message = logEvent.RenderMessage(_formatProvider);
        
        string exception =
            logEvent.Exception?.Message ?? (logEvent.Level >= LogEventLevel.Error
                ? message
                : string.Empty);

        LogEntryColor color = config.Colors[logLevel];

        AddLogEntry(logLevel, eventId, message, exception, color);
    }

    protected virtual void AddLogEntry(
        LogLevel logLevel,
        EventId eventId,
        string message,
        string exception,
        LogEntryColor color)
    {
        ILogDataStore? dataStore = _dataStoreProvider.Invoke();

        // ReSharper disable once 
        // ConditionIsAlwaysTrueOrFalseAccordingToNullableAPIContract
        if (dataStore == null)
            return; // app is shutting down

        dataStore.AddEntry(new()
        {
            Timestamp = DateTime.UtcNow,
            LogLevel = logLevel,
            EventId = eventId,
            State = message,
            Exception = exception,
            Color = color
        });
    }

    private static EventId EventIdFactory(LogEvent logEvent)
    {
        EventId eventId;
        if (!logEvent.Properties.TryGetValue("EventId", out LogEventPropertyValue? src))
            return new();
        
        int? id = null;
        string? eventName = null;

        StructureValue? value = src as StructureValue;

        LogEventProperty? idProperty
          = value!.Properties.FirstOrDefault(x => x.Name.Equals("Id"));

        if (idProperty is not null)
            id = int.Parse(idProperty.Value.ToString());

        LogEventProperty? nameProperty
          = value.Properties.FirstOrDefault(x => x.Name.Equals("Name"));

        if (nameProperty is not null)
            eventName = nameProperty.Value.ToString().Trim('"');

        eventId = new EventId(id ?? 0, eventName ?? string.Empty);

        return eventId;
    }
}

Public Class DataStoreLoggerSink : Implements ILogEventSink

  Protected ReadOnly _dataStoreProvider As Func(Of ILogDataStore)

  Private ReadOnly _formatProvider As IFormatProvider
  Private ReadOnly _getCurrentConfig As Func(Of DataStoreLoggerConfiguration)

  Public Sub New(dataStoreProvider As Func(Of ILogDataStore),
         Optional getCurrentConfig As Func(Of DataStoreLoggerConfiguration) = Nothing,
         Optional formatProvider As IFormatProvider = Nothing)
    _dataStoreProvider = dataStoreProvider
    _formatProvider = formatProvider
    _getCurrentConfig = getCurrentConfig
  End Sub


  Public Sub Emit(logEvent As LogEvent) Implements ILogEventSink.Emit

    Dim logLevel As LogLevel

    Select Case logEvent.Level
      Case LogEventLevel.Verbose : logLevel = LogLevel.Trace
      Case LogEventLevel.Debug : logLevel = LogLevel.Debug
      Case LogEventLevel.Warning : logLevel = LogLevel.Warning
      Case LogEventLevel.Error : logLevel = LogLevel.Error
      Case LogEventLevel.Fatal : logLevel = LogLevel.Critical
      Case Else : logLevel = LogLevel.Information
    End Select

    Dim config As DataStoreLoggerConfiguration = If(_getCurrentConfig Is Nothing,
                            New DataStoreLoggerConfiguration(),
                            _getCurrentConfig.Invoke())

    Dim eventId As EventId = EventIdFactory(logEvent)
    If eventId.Id = 0 AndAlso config.EventId <> 0 Then
      eventId = config.EventId
    End If

    Dim message As String = logEvent.RenderMessage(_formatProvider)

    Dim exception As String = If(logEvent.Exception Is Nothing,
                  If(logEvent.Level >= LogEventLevel.Error, message, String.Empty),
                  logEvent.Exception.Message)

    Dim color As LogEntryColor = config.Colors(logLevel)

    AddLogEntry(logLevel, eventId, message, exception, color)

  End Sub

  Protected Overridable Sub AddLogEntry(logLevel As LogLevel, eventId As EventId,
                                        message As String, exception As String,
                                        color As LogEntryColor)

    Dim dataStore As ILogDataStore = _dataStoreProvider.Invoke()

    If dataStore Is Nothing Then
      Return
    End If

    dataStore.AddEntry(
      New LogModel() With
      {
        .Timestamp = DateTime.UtcNow,
        .LogLevel = logLevel,
        .EventId = eventId,
        .State = message,
        .Exception = exception,
        .Color = color
      })

  End Sub

  Private Shared Function EventIdFactory(logEvent As LogEvent) As EventId

    Dim eventId As EventId
    Dim src As LogEventPropertyValue

    If Not logEvent.Properties.TryGetValue("EventId", src) Then
      Return New EventId()
    End If

    Dim id As Integer = Nothing
    Dim eventName As String = Nothing

    ' ref: https://stackoverflow.com/a/56722516
    Dim value As StructureValue = DirectCast(src, StructureValue)

    Dim idProperty As LogEventProperty
      = value.Properties.FirstOrDefault(Function(x) x.Name.Equals("Id"))

    If idProperty IsNot Nothing Then
      id = Integer.Parse(idProperty.Value.ToString())
    End If

    Dim nameProperty As LogEventProperty
      = value.Properties.FirstOrDefault(Function(x) x.Name.Equals("Name"))

    If nameProperty IsNot Nothing Then
      eventName = nameProperty.Value.ToString().Trim(""""c)
    End If

    eventId = New EventId(
      If(id = Nothing, 0, id),
      If(String.IsNullOrWhiteSpace(eventName), String.Empty, eventName))

    Return eventId

  End Function

End Class

public static class DataStoreLoggerSinkExtensions
{
    public static LoggerConfiguration DataStoreLoggerSink
    (
        this LoggerSinkConfiguration loggerConfiguration,
        Func<ILogDataStore> dataStoreProvider, 
        Action<DataStoreLoggerConfiguration>? configuration = null,
        IFormatProvider formatProvider = null!
    )
        => loggerConfiguration.Sink(
            new DataStoreLoggerSink(
                dataStoreProvider,
                GetConfig(configuration),
                formatProvider));

    private static Func<DataStoreLoggerConfiguration> GetConfig(
        Action<DataStoreLoggerConfiguration>? configuration)
    {
        // convert from Action to Func delegate to pass data
        DataStoreLoggerConfiguration data = new();
        configuration?.Invoke(data);
        return () => data;
    }
}

Public Module DataStoreLoggerSinkExtensions

  <Extension>
  Public Function DataStoreLoggerSink(loggerConfiguration As LoggerSinkConfiguration,
                    dataStoreProvider As Func(Of ILogDataStore),
                    Optional configuration As Action_
                    (Of DataStoreLoggerConfiguration) = Nothing,
                    Optional formatProvider As IFormatProvider = Nothing) _
                    As LoggerConfiguration

    Return loggerConfiguration.Sink(
      New DataStoreLoggerSink(dataStoreProvider,
                              GetConfig(configuration),
                              formatProvider))

  End Function

  Private Function GetConfig(configuration As Action(Of DataStoreLoggerConfiguration))
    As Func(Of DataStoreLoggerConfiguration)

    Dim data As DataStoreLoggerConfiguration = New DataStoreLoggerConfiguration()

    If configuration IsNot Nothing Then
      configuration.Invoke(data)
    End If

    Return Function() data

  End Function

End Module

HostApplicationBuilder builder = Host.CreateApplicationBuilder();

builder.AddLogViewer();

IServiceCollection services = builder.Services;

services.AddLogging(configure: cfg =>
{
    Log.Logger = new LoggerConfiguration()
        .ReadFrom.Configuration(builder.Configuration)
        .WriteTo.DataStoreLoggerSink(

            // Use Default Colors
            dataStoreProvider: () => _host!.Services.TryGetService<ILogDataStore>()!)
        .CreateLogger();

    cfg.ClearProviders()
        .AddSerilog(Log.Logger);
});

_host = builder.Build();

Dim builder As HostApplicationBuilder = Host.CreateApplicationBuilder()

builder.AddLogViewer()

Dim services As IServiceCollection = builder.Services

services.AddLogging(
 Sub(cfg)

  ' Use Default Colors
  Log.Logger = New LoggerConfiguration() _
    .ReadFrom.Configuration(builder.Configuration) _
    .WriteTo.DataStoreLoggerSink(
    Function() _host.Services.TryGetService(Of ILogDataStore)) _
  .CreateLogger()

  cfg.ClearProviders() _
   .AddSerilog(Log.Logger)

 End Sub)

_host = builder.Build()

HostApplicationBuilder builder = Host.CreateApplicationBuilder();

builder.AddLogViewer();
IServiceCollection services = builder.Services;

services.AddLogging(configure: cfg =>
{
    Log.Logger = new LoggerConfiguration()
        .ReadFrom.Configuration(builder.Configuration)
        .WriteTo.DataStoreLoggerSink(

        // Use Custom Colors
        dataStoreProvider: () => _host!.Services.TryGetService<ILogDataStore>()!,
        options =>
        {
            options.Colors[LogLevel.Trace] = new()
            {
                Foreground = Color.White,
                Background = Color.DarkGray
            };
        
            options.Colors[LogLevel.Debug] = new()
            {
                Foreground = Color.White,
                Background = Color.Gray
            };
        
            options.Colors[LogLevel.Information] = new()
            {
                Foreground = Color.White,
                Background = Color.DodgerBlue
            };
        
            options.Colors[LogLevel.Warning] = new()
            {
                Foreground = Color.White,
                Background = Color.Orchid
            };
        })
        .CreateLogger();

    cfg.ClearProviders()
        .AddSerilog(Log.Logger);
});

_host = builder.Build();

Dim builder As HostApplicationBuilder = Host.CreateApplicationBuilder()

builder.AddLogViewer()

Dim services As IServiceCollection = builder.Services

services.AddLogging(
 Sub(cfg)

  ' Use Custom Colors
  Log.Logger = New LoggerConfiguration() _
    .ReadFrom.Configuration(builder.Configuration) _
    .WriteTo.DataStoreLoggerSink(
     Function() _host.Services.TryGetService(Of ILogDataStore),
     Sub(options)
      options.Colors(LogLevel.Trace) = New LogEntryColor() With
      {
       .Foreground = Color.White,
       .Background = Color.DarkGray
      }

      options.Colors(LogLevel.Debug) = New LogEntryColor() With
      {
       .Foreground = Color.White,
       .Background = Color.Gray
      }

      options.Colors(LogLevel.Information) = New LogEntryColor() With
      {
       .Foreground = Color.White,
       .Background = Color.DodgerBlue
      }

      options.Colors(LogLevel.Warning) = New LogEntryColor() With
      {
       .Foreground = Color.White,
       .Background = Color.Orchid
      }

     End Sub) _
    .CreateLogger()

  cfg.ClearProviders() _
   .AddSerilog(Log.Logger)

 End Sub)

_host = builder.Build()

public class RandomLoggingService : BackgroundService
{
    #region Constructors

    public RandomLoggingService(ILogger<RandomLoggingService> logger)
        => _logger = logger;

    #endregion

    #region Fields

    private readonly ILogger _logger;

    #endregion
}

Public Class RandomLoggingService : Inherits BackgroundService

#Region "Constructors"

  Public Sub New(logger As ILogger(Of RandomLoggingService))

    _logger = logger

  End Sub

#End Region

#Region "Fields"

  Private _logger As ILogger

#End Region

End Class

ILogger<class> logger = _host.Services.GetRequiredService<ILogger<class>>();

Dim logger As ILogger(Of class_name) =
    _host.Services.GetRequiredService(Of ILogger(Of class_name))

public static class LoggingHelper
{
    #region Constructors

    static LoggingHelper()
    {
        IConfigurationRoot configuration = new ConfigurationBuilder()
            .Initialize()
            .Build();

        Log.Logger = new LoggerConfiguration()
            .ReadFrom.Configuration(configuration)
            .WriteTo.DataStoreLoggerSink(
            
                // Use Default Colors
                dataStoreProvider: () => MainControlsDataStore.DataStore)
            .CreateLogger();

        // wire up the loggers
        Factory = LoggerFactory.Create(loggingBuilder
            => loggingBuilder.AddSerilog(Log.Logger));
    }

    #endregion

    #region Properties

    public static ILoggerFactory Factory { get; }

    #endregion

    #region Methods

    public static void CloseAndFlush()
        => Log.CloseAndFlush();

    #endregion
}

Public Module LoggingHelper

#Region "Constructors"

 Sub New()

  Dim configuration As IConfigurationRoot = New ConfigurationBuilder() _
   .Initialize() _
   .Build()

  ' Use Default Colors
  Log.Logger = New LoggerConfiguration() _
  .ReadFrom.Configuration(configuration) _
  .WriteTo.DataStoreLoggerSink(Function() MainControlsDataStore.DataStore) _
  .CreateLogger()

  ' wire up the loggers
  Factory = LoggerFactory.Create(
    Sub(LoggingBuilder)
      LoggingBuilder.AddSerilog(Log.Logger)
    End Sub)

 End Sub

#End Region

#Region "Properties"

 Public ReadOnly Property Factory As ILoggerFactory

#End Region

#Region "Methods"

 Friend Sub CloseAndFlush()

  Log.CloseAndFlush()

 End Sub

#End Region

End Module

public static class LoggingHelper
{
    #region Constructors

    static LoggingHelper()
    {
        IConfigurationRoot configuration = new ConfigurationBuilder()
            .Initialize()
            .Build();

       // Use Custom Colors
        Log.Logger = new LoggerConfiguration()
            .ReadFrom.Configuration(configuration)
            .WriteTo.DataStoreLoggerSink(
                dataStoreProvider: () => MainControlsDataStore.DataStore,
                options =>
                {
                    options.Colors[LogLevel.Trace] = new()
                    {
                        Foreground = Color.White,
                        Background = Color.DarkGray
                    };

                    options.Colors[LogLevel.Debug] = new()
                    {
                        Foreground = Color.White,
                        Background = Color.Gray
                    };

                    options.Colors[LogLevel.Information] = new()
                    {
                        Foreground = Color.White,
                        Background = Color.DodgerBlue
                    };

                    options.Colors[LogLevel.Warning] = new()
                    {
                        Foreground = Color.White,
                        Background = Color.Orchid
                    };
                }
            )
            .CreateLogger();

        // wire up the loggers
        Factory = LoggerFactory.Create(loggingBuilder => 
                  loggingBuilder.AddSerilog(Log.Logger));
    }

    #endregion

    #region Properties

    public static ILoggerFactory Factory { get; }

    #endregion

    #region Methods

    public static void CloseAndFlush()
        => Log.CloseAndFlush();

    #endregion
}

Public Module LoggingHelper

#Region "Constructors"

 Sub New()

  Dim configuration As IConfigurationRoot = New ConfigurationBuilder() _
   .Initialize() _
   .Build()

  ' Use Custom Colors
  Log.Logger = New LoggerConfiguration() _
   .ReadFrom.Configuration(configuration) _
   .WriteTo.DataStoreLoggerSink(
    Function() MainControlsDataStore.DataStore,
    Sub(options)

     options.Colors(LogLevel.Trace) = New LogEntryColor() With
     {
      .Foreground = Color.White,
      .Background = Color.DarkGray
     }

     options.Colors(LogLevel.Debug) = New LogEntryColor() With
     {
      .Foreground = Color.White,
      .Background = Color.Gray
     }

     options.Colors(LogLevel.Information) = New LogEntryColor() With
     {
      .Foreground = Color.White,
      .Background = Color.DodgerBlue
     }

     options.Colors(LogLevel.Warning) = New LogEntryColor() With
     {
      .Foreground = Color.White,
      .Background = Color.Orchid
     }

    End Sub) _
   .CreateLogger()

  ' wire up the loggers
  Factory = LoggerFactory.Create(Sub(LoggingBuilder) 
            LoggingBuilder.AddSerilog(Log.Logger))

 End Sub

#End Region

#Region "Properties"

 Public ReadOnly Property Factory As ILoggerFactory

#End Region

#Region "Methods"

 Friend Sub CloseAndFlush()

  Log.CloseAndFlush()

 End Sub

#End Region

End Module

Logger<class> logger = new Logger<class>(LoggingHelper.Factory);

Dim logger As Logger(Of class_name) = New Logger(Of class_name)(LoggingHelper.Factory)

RandomLoggingService service = 
    new(new Logger<RandomLoggingService>(LoggingHelper.Factory));

Dim service As RandomLoggingService =
    New RandomLoggingService(New Logger(Of RandomLoggingService)(LoggingHelper.Factory))

[Target("DataStoreLogger")]
public class DataStoreLoggerTarget : TargetWithLayout
{
    #region Fields

    private ILogDataStore? _dataStore;
    private DataStoreLoggerConfiguration? _config;

    #endregion

    #region methods

    protected override void InitializeTarget()
    {
        // we need to inject dependencies
        IServiceProvider serviceProvider = ResolveService<IServiceProvider>();

        // reference the shared instance
        _dataStore = serviceProvider.GetRequiredService<ILogDataStore>();

        // load the config options
        IOptionsMonitor<DataStoreLoggerConfiguration>? options
        = serviceProvider.GetService<IOptionsMonitor<DataStoreLoggerConfiguration>>();

        _config = options?.CurrentValue ?? new DataStoreLoggerConfiguration();

        base.InitializeTarget();
    }

    protected override void Write(LogEventInfo logEvent)
    {
        // cast NLog Loglevel to Microsoft LogLevel type
        MsLogLevel logLevel
          = (MsLogLevel)Enum.ToObject(typeof(MsLogLevel), logEvent.Level.Ordinal);

        // format the message
        string message = RenderLogEvent(Layout, logEvent);

        // retrieve the EventId
        EventId eventId = (EventId)logEvent.Properties["EventId"];

        // add log entry
        _dataStore?.AddEntry(new()
        {
            Timestamp = DateTime.UtcNow,
            LogLevel = logLevel,
            // do we override the default EventId if it exists?
            EventId = eventId.Id == 0 &&
                      (_config?.EventId.Id ?? 0) != 0
                        ? _config!.EventId
                        : eventId,
            State = message,
            Exception = logEvent.Exception?.Message ??
                      (logLevel == MsLogLevel.Error ? message : ""),
            Color = _config!.Colors[logLevel],
        });
        
        Debug.WriteLine(
            $"--- [{logLevel.ToString()[..3]}]
            {message} - {logEvent.Exception?.Message ?? "no error"}");
    }

    #endregion
}

<target("datastorelogger")>
Public Class DataStoreLoggerTarget : Inherits TargetWithLayout

#Region "Fields"

    Private _dataStore As ILogDataStore
    Private _config As DataStoreLoggerConfiguration

#End Region

#Region "methods"

    Protected Overrides Sub InitializeTarget()

        ' we need to inject dependencies
        Dim serviceProvider As IServiceProvider = ResolveService(Of IServiceProvider)()

        ' reference the shared instance
        _dataStore = serviceProvider.GetRequiredService(Of ILogDataStore)

        ' load the config options
        Dim options As IOptionsMonitor(Of DataStoreLoggerConfiguration) _
            = serviceProvider.GetService(Of IOptionsMonitor(Of DataStoreLoggerConfiguration))

        _config =
          If(options Is Nothing, _
             New DataStoreLoggerConfiguration(), _
             options.CurrentValue)

        MyBase.InitializeTarget()

    End Sub

    Protected Overrides Sub Write(logEvent As LogEventInfo)

        ' cast NLog Loglevel to Microsoft LogLevel type
        Dim logLevel As MsLogLevel
          = [Enum].ToObject(GetType(MsLogLevel), logEvent.Level.Ordinal)

        ' format the message
        Dim message As String = RenderLogEvent(Layout, logEvent)

        ' retrieve the EventId
        Dim eventId As EventId = logEvent.Properties("EventId")

        If eventId.Id = 0 AndAlso _config.EventId.Id <> 0 Then
            eventId = _config.EventId
        End If

        Dim exMessage As String = String.Empty

        If logEvent.Exception IsNot Nothing Then
            If String.IsNullOrEmpty(logEvent.Exception.Message) Then
                If logLevel = MsLogLevel.Error AndAlso message IsNot Nothing Then
                    exMessage = message.ToString()
                End If
            Else
                exMessage = logEvent.Exception.Message
            End If
        End If

        ' add log entry
        _dataStore.AddEntry(New LogModel() With
        {
            .Timestamp = Date.UtcNow,
           .LogLevel = logLevel,
           .EventId = eventId,
           .State = message,
           .Exception = exMessage,
           .Color = _config.Colors(logLevel)
        })

        Debug.WriteLine(
          $"--- [{logLevel.ToString()(0.3)}] {message} - " + 
          $"{If(String.IsNullOrWhiteSpace(exMessage), "no error", exMessage)}")

        MyBase.Write(logEvent)

    End Sub

#End Region

End Class

public static class ServicesExtension
{
    public static ILoggingBuilder AddNLogTargets(
        this ILoggingBuilder builder, IConfiguration config)
    {
        LogManager
            .Setup()
            // Register custom Target
            .SetupExtensions(extensionBuilder =>
            extensionBuilder.RegisterTarget<DataStoreLoggerTarget>("DataStoreLogger"));

        builder
            .ClearProviders()
            .SetMinimumLevel(MsLogLevel.Trace)
            .AddNLog(config,
                new NLogProviderOptions
                {
                    IgnoreEmptyEventId = false,
                    CaptureEventId = EventIdCaptureType.Legacy
                });

        return builder;
    }

    public static ILoggingBuilder AddNLogTargets(
        this ILoggingBuilder builder, IConfiguration config,
        Action<DataStoreLoggerConfiguration> configure)
    {
        builder.AddNLogTargets(config);
        builder.Services.Configure(configure);
        return builder;
    }
}

Public Module ServicesExtension

    <extension>
    Public Function AddNLogTargets( _
        builder As ILoggingBuilder, config As IConfiguration) As ILoggingBuilder

        LogManager _
            .Setup() _
            .SetupExtensions(
                Sub(extensionBuilder) _
                    extensionBuilder.RegisterTarget(Of DataStoreLoggerTarget)
                    ("DataStoreLogger"))

        builder _
            .ClearProviders() _
            .SetMinimumLevel(MsLogLevel.Trace) _
            .AddNLog(config,
                New NLogProviderOptions With
                {
                    .IgnoreEmptyEventId = False,
                    .CaptureEventId = EventIdCaptureType.Legacy
                })

        Return builder

    End Function

    <extension>
    Public Function AddNLogTargets( _
        builder As ILoggingBuilder, config As IConfiguration, _
        configure As Action(Of DataStoreLoggerConfiguration)) As ILoggingBuilder

        builder.AddNLogTargets(config)
        builder.Services.Configure(configure)
        Return builder

    End Function

End Module

HostApplicationBuilder builder = Host.CreateApplicationBuilder();

builder.AddLogViewer();

builder.Logging.AddNLogTargets(builder.Configuration);

_host = builder.Build();

Dim builder As HostApplicationBuilder = Host.CreateApplicationBuilder()

builder.AddLogViewer()

builder.Logging.AddNLogTargets(builder.Configuration);

_host = builder.Build()

HostApplicationBuilder builder = Host.CreateApplicationBuilder();

builder.AddLogViewer();

builder.Logging.AddNLogTargets(builder.Configuration, options =>
{
    options.Colors[LogLevel.Trace] = new()
    {
        Foreground = Color.White,
        Background = Color.DarkGray
    };

    options.Colors[LogLevel.Debug] = new()
    {
        Foreground = Color.White,
        Background = Color.Gray
    };

    options.Colors[LogLevel.Information] = new()
    {
        Foreground = Color.White,
        Background = Color.DodgerBlue
    };

    options.Colors[LogLevel.Warning] = new()
    {
        Foreground = Color.White,
        Background = Color.Orchid
    };
});

_host = builder.Build();

Dim builder As HostApplicationBuilder = Host.CreateApplicationBuilder()

builder.AddLogViewer()

builder.Logging.AddNLogTargets(
    builder.Configuration,
    Sub(options)

        options.Colors(LogLevel.Trace) = New LogEntryColor() With
        {
            .Foreground = Color.White,
            .Background = Color.DarkGray
        }

        options.Colors(LogLevel.Debug) = New LogEntryColor() With
        {
            .Foreground = Color.White,
            .Background = Color.Gray
        }

        options.Colors(LogLevel.Information) = New LogEntryColor() With
        {
            .Foreground = Color.White,
            .Background = Color.DodgerBlue
        }

        options.Colors(LogLevel.Warning) = New LogEntryColor() With
        {
            .Foreground = Color.White,
            .Background = Color.Orchid
        }

    End Sub)

_host = builder.Build()

public class RandomLoggingService : BackgroundService
{
#region Constructors

    public RandomLoggingService(ILogger<RandomLoggingService> logger)
        => _logger = logger;

    #endregion

    #region Fields

    private readonly ILogger _logger;

    #endregion
}

Public Class RandomLoggingService : Inherits BackgroundService

#Region "Constructors"

  Public Sub New(logger As ILogger(Of RandomLoggingService))

    _logger = logger

  End Sub

#End Region

#Region "Fields"

  Private _logger As ILogger

#End Region

End Class

ILogger<class> logger
    = _host.Services.GetRequiredService<ILogger<class>>();

Dim logger As ILogger(Of class_name)
  = _host.Services.GetRequiredService(Of ILogger(Of class_name))

public static class ServicesExtension
{
    public static ILoggingBuilder AddNLogTargetsNoDI(
        this ILoggingBuilder builder, IConfiguration config)
    {
        // We need to use a shared instance of the DataStore to
        //  pass to the LogViewerControl
        builder.Services.AddSingleton(MainControlsDataStore.DataStore);

        // call core NLog ServiceExtension initializer
        builder.AddNLogTargets(config);

        return builder;
    }

    public static ILoggingBuilder AddNLogTargetsNoDI(
        this ILoggingBuilder builder, IConfiguration config,
        Action<DataStoreLoggerConfiguration> configure)
    {
        builder.AddNLogTargetsNoDI(config);
        builder.Services.Configure(configure);
        return builder;
    }
}

Public Module ServicesExtension

    <extension>
    Public Function AddNLogTargetsNoDI( _
        builder As ILoggingBuilder, _
        config As IConfiguration) As ILoggingBuilder

        ' We need to use a shared instance of the DataStore to
        '  pass to the LogViewerControl
        builder.Services.AddSingleton(MainControlsDataStore.DataStore)

        ' call core NLog ServiceExtension initializer
        builder.AddNLogTargets(config)

        Return builder

    End Function

    <extension>
    Public Function AddNLogTargetsNoDI( _
        builder As ILoggingBuilder, config As IConfiguration, _
        configure As Action(Of DataStoreLoggerConfiguration)) As ILoggingBuilder

        builder.AddNLogTargetsNoDI(config)
        builder.Services.Configure(configure)
        Return builder

    End Function

End Module

public static class LoggingHelper
{
    #region Constructors

    static LoggingHelper()
    {
        // retrieve the log level from 'appsettings'
        string value = AppSettings<string>
            .Current("Logging:LogLevel", "Default") ?? "Information";
        Enum.TryParse(value, out LogLevel logLevel);

        IConfigurationRoot configuration = new ConfigurationBuilder()
            .Initialize()
            .Build();

        // wire up the loggers
        Factory = LoggerFactory.Create(builder => builder

            // visual debugging tools
            .AddNLogTargetsNoDI(configuration)

            // set minimum log level from 'appsettings*.json'
            .SetMinimumLevel(logLevel));
    }

    #endregion

    #region Properties

    public static ILoggerFactory Factory { get; }

    #endregion
}

Public Module LoggingHelper

#Region "Constructors"

	Sub New()

		' retrieve the log level from 'appsettings'
		Dim value As String = AppSettings(Of String) _
            .Current("Logging:LogLevel", "Default")

		If String.IsNullOrWhiteSpace(value) Then
			value = "Information"
		End If

		Dim logLevel As LogLevel
		If Not [Enum].TryParse(value, logLevel) Then
			logLevel = LogLevel.Information
		End If

		Dim configuration As IConfigurationRoot = New ConfigurationBuilder() _
			.Initialize() _
			.Build()

		' wire up the loggers
		Factory = LoggerFactory.Create(
			Sub(builder)

				builder.AddNLogTargetsNoDI(configuration)

				' set minimum log level from 'appsettings'
				builder.SetMinimumLevel(logLevel)

			End Sub)

	End Sub

#End Region

#Region "Properties"

	Public ReadOnly Property Factory As ILoggerFactory

#End Region

End Module

public static class LoggingHelper
{
    #region Constructors

    static LoggingHelper()
    {
        // retrieve the log level from 'appsettings'
        string value = AppSettings<string>
            .Current("Logging:LogLevel", "Default") ?? "Information";

        Enum.TryParse(value, out LogLevel logLevel);

        IConfigurationRoot configuration = new ConfigurationBuilder()
            .Initialize()
            .Build();


        // wire up the loggers
        Factory = LoggerFactory.Create(builder => builder

            // visual debugging tools
            .AddNLogTargetsNoDI(configuration, options =>
            {
                options.Colors[LogLevel.Trace] = new()
                {
                    Foreground = Color.White,
                    Background = Color.DarkGray
                };

                options.Colors[LogLevel.Debug] = new()
                {
                    Foreground = Color.White,
                    Background = Color.Gray
                };

                options.Colors[LogLevel.Information] = new()
                {
                    Foreground = Color.White,
                    Background = Color.DodgerBlue
                };

                options.Colors[LogLevel.Warning] = new()
                {
                    Foreground = Color.White,
                    Background = Color.Orchid
                };
            })

            // set minimum log level from 'appsettings*.json'
            .SetMinimumLevel(logLevel));
    }

    #endregion

    #region Properties

    public static ILoggerFactory Factory { get; }

    #endregion
}

Public Module LoggingHelper

#Region "Constructors"

	Sub New()

		' retrieve the log level from 'appsettings'
		Dim value As String = AppSettings(Of String) _
            .Current("Logging:LogLevel", "Default")

		If String.IsNullOrWhiteSpace(value) Then
			value = "Information"
		End If

		Dim logLevel As LogLevel
		If Not [Enum].TryParse(value, logLevel) Then
			logLevel = LogLevel.Information
		End If

		Dim configuration As IConfigurationRoot = New ConfigurationBuilder() _
			.Initialize() _
			.Build()

		' wire up the loggers
		Factory = LoggerFactory.Create(
			Sub(builder)

				builder.AddNLogTargetsNoDI(
					configuration,
					Sub(options)

						options.Colors(LogLevel.Trace) = New LogEntryColor() With
						{
							.Foreground = Color.White,
							.Background = Color.DarkGray
						}

						options.Colors(LogLevel.Debug) = New LogEntryColor() With
						{
							.Foreground = Color.White,
							.Background = Color.Gray
						}

						options.Colors(LogLevel.Information) = New LogEntryColor() With
						{
							.Foreground = Color.White,
							.Background = Color.DodgerBlue
						}

						options.Colors(LogLevel.Warning) = New LogEntryColor() With
						{
							.Foreground = Color.White,
							.Background = Color.Orchid
						}

					End Sub)

				' set minimum log level from 'appsettings'
				builder.SetMinimumLevel(logLevel)

			End Sub)

	End Sub

#End Region

#Region "Properties"

	Public ReadOnly Property Factory As ILoggerFactory

#End Region

End Module

Logger<class> logger
    = new Logger<class>(LoggingHelper.Factory);

Dim logger As Logger(Of class_name)
  = New Logger(Of class_name)(LoggingHelper.Factory)

RandomLoggingService service
    = new(new Logger<RandomLoggingService>(LoggingHelper.Factory));

Dim service As RandomLoggingService
  = New RandomLoggingService(New Logger(Of RandomLoggingService)(LoggingHelper.Factory))

public class DataStoreLoggerAppender : AppenderServiceProvider
{
    #region Fields

    private ILogDataStore? _dataStore;
    private DataStoreLoggerConfiguration? _options;
    
    private IServiceProvider? _serviceProvider;
    
    #endregion

    #region Methods

    protected override void Append(LoggingEvent loggingEvent)
    {
        if (_serviceProvider is null)
            Initialize();

        // cast matching Log4Net Loglevel to Microsoft LogLevel type
        LogLevel logLevel = loggingEvent.Level.Value switch 
        {
            int.MaxValue => LogLevel.None,
            120000 => LogLevel.Debug,
            90000 => LogLevel.Critical,
            70000 => LogLevel.Error,
            60000 => LogLevel.Warning,
            20000 => LogLevel.Trace,
            _ => LogLevel.Information
        };

        DataStoreLoggerConfiguration config = _options ?? 
new DataStoreLoggerConfiguration();

        EventId? eventId = (EventId?)loggingEvent.LookupProperty(nameof(EventId));
        eventId = eventId is null && config.EventId.Id != 0 ? 
                                     config.EventId : eventId;

        string message = loggingEvent.RenderedMessage ?? string.Empty;
        
        string exceptionMessage = loggingEvent.GetExceptionString();

        _dataStore!.AddEntry(new()
        {
            Timestamp = DateTime.UtcNow,
            LogLevel = logLevel,
            EventId = eventId ?? new(),
            State = message,
            Exception = exceptionMessage,
            Color = config.Colors[logLevel],
        });

        Debug.WriteLine($"--- [{logLevel.ToString()[..3]}] {message}
            - {exceptionMessage ?? "no error"}");
    }

    private void Initialize()
    {
        _serviceProvider = ResolveService<IServiceProvider>();
        _dataStore = _serviceProvider.GetRequiredService<ILogDataStore>();
        _options = _serviceProvider.GetService<DataStoreLoggerConfiguration>();
    }

    #endregion
}

Public Class DataStoreLoggerAppender : Inherits ServiceAppenderSkeleton

#Region "Fields"

    Private _dataStore As ILogDataStore
    Private _options As DataStoreLoggerConfiguration

    Private _serviceProvider As IServiceProvider

#End Region

#Region "Methods"

    Protected Overrides Sub Append(loggingEvent As LoggingEvent)

        If _serviceProvider Is Nothing Then
            Initialize()
        End If

        ' cast matching Log4Net Loglevel to Microsoft LogLevel type
        Dim logLevel As LogLevel

        Select Case loggingEvent.Level.Value
            Case Integer.MaxValue : logLevel = LogLevel.None
            Case 120000 : logLevel = LogLevel.Debug
            Case 90000 : logLevel = LogLevel.Critical
            Case 70000 : logLevel = LogLevel.Error
            Case 60000 : logLevel = LogLevel.Warning
            Case 20000 : logLevel = LogLevel.Trace
            Case Else : logLevel = LogLevel.Information
        End Select

        Dim config As DataStoreLoggerConfiguration =
            If(_options Is Nothing, New DataStoreLoggerConfiguration, _options)

        Dim eventId As EventId = loggingEvent.LookupProperty(NameOf(eventId))
        eventId = If(eventId = Nothing AndAlso config.EventId.Id <> 0, _
                                               config.EventId, eventId)

        Dim message As String = loggingEvent.RenderedMessage

        Dim exceptionMessage = loggingEvent.GetExceptionString()

        _dataStore.AddEntry(
            New LogModel() With
            {
                .Timestamp = Date.UtcNow,
                .LogLevel = logLevel,
                .State = message,
                .Exception = exceptionMessage,
                .Color = config.Colors(logLevel)
            })

        Debug.WriteLine($"--- [{logLevel.ToString()(0.3)}] {message}" +
            " - {If(String.IsNullOrWhiteSpace(exceptionMessage), _
                 "no error", exceptionMessage)}")

    End Sub

    Private Sub Initialize()

        _serviceProvider = ResolveService(Of IServiceProvider)()
        _dataStore = _serviceProvider.GetRequiredService(Of ILogDataStore)
        _options = _serviceProvider.GetService(Of DataStoreLoggerConfiguration)

    End Sub

#End Region

End Class

public static class ServicesExtension
{
    public static ILoggingBuilder AddLog4Net_
           (this ILoggingBuilder builder, IConfiguration config)
        => builder
            .ClearProviders()
            .AddLog4Net(config.GetLog4NetConfiguration());

    public static ILoggingBuilder AddLog4Net(this ILoggingBuilder builder,
        IConfiguration config, Action<DataStoreLoggerConfiguration> configure)
    {
        builder
            .AddLog4Net(config)
            .Services.Configure(configure);

        return builder;
    }

    public static Log4NetProviderOptions? GetLog4NetConfiguration(
        this IConfiguration configuration)
        => configuration
            .GetSection("Log4NetCore")
            .Get<Log4NetProviderOptions>();
}

Public Module ServicesExtension

    <extension>
    Public Function AddLog4Net(builder As ILoggingBuilder,
        config As IConfiguration) As ILoggingBuilder

        builder _
            .ClearProviders() _
            .AddLog4Net(config.GetLog4NetConfiguration())

        Return builder

    End Function

    <extension>
    Public Function AddLog4Net(builder As ILoggingBuilder,
        config As IConfiguration, _
        configure As Action(Of DataStoreLoggerConfiguration))
        As ILoggingBuilder

        builder.AddLog4Net(config)
        builder.Services.Configure(configure)
        Return builder

    End Function

    <extension>
    Private Function GetLog4NetConfiguration(configuration As IConfiguration)
        As Log4NetProviderOptions

        Return configuration _
            .GetSection("Log4NetCore") _
            .Get(Of Log4NetProviderOptions)

    End Function

End Module

HostApplicationBuilder builder = Host.CreateApplicationBuilder();

builder.AddLogViewer();

builder.Logging.AddLog4Net(builder.Configuration);

_host = builder.Build();

Dim builder As HostApplicationBuilder = Host.CreateApplicationBuilder()

builder.AddLogViewer()

builder.Logging.AddLog4Net(builder.Configuration)

_host = builder.Build()

HostApplicationBuilder builder = Host.CreateApplicationBuilder();

builder.AddLogViewer();

builder.Logging.AddLog4Net(builder.Configuration, options =>
{
options.Colors[LogLevel.Trace] = new()
{
Foreground = Color.White,
Background = Color.DarkGray
};

    options.Colors[LogLevel.Debug] = new()
    {
        Foreground = Color.White,
        Background = Color.Gray
    };

    options.Colors[LogLevel.Information] = new()
    {
        Foreground = Color.White,
        Background = Color.DodgerBlue
    };

    options.Colors[LogLevel.Warning] = new()
    {
        Foreground = Color.White,
        Background = Color.Orchid
    };
});

_host = builder.Build();

Dim builder As HostApplicationBuilder = Host.CreateApplicationBuilder()

builder.AddLogViewer()

builder.Logging.AddLog4Net(
    builder.Configuration,
    Sub(options)

        options.Colors(LogLevel.Trace) = New LogEntryColor() With
        {
            .Foreground = Color.White,
            .Background = Color.DarkGray
        }

        options.Colors(LogLevel.Debug) = New LogEntryColor() With
        {
            .Foreground = Color.White,
            .Background = Color.Gray
        }

        options.Colors(LogLevel.Information) = New LogEntryColor() With
        {
            .Foreground = Color.White,
            .Background = Color.DodgerBlue
        }

        options.Colors(LogLevel.Warning) = New LogEntryColor() With
        {
            .Foreground = Color.White,
            .Background = Color.Orchid
        }

    End Sub)

_host = builder.Build()

public class RandomLoggingService : BackgroundService
{
#region Constructors

    public RandomLoggingService(ILogger<RandomLoggingService> logger)
        => _logger = logger;

    #endregion

    #region Fields

    private readonly ILogger _logger;

    #endregion
}

Public Class RandomLoggingService : Inherits BackgroundService

#Region "Constructors"

  Public Sub New(logger As ILogger(Of RandomLoggingService))

    _logger = logger

  End Sub

#End Region

#Region "Fields"

  Private _logger As ILogger

#End Region

End Class

ILogger<class> logger
    = _host.Services.GetRequiredService<ILogger<class>>();

Dim logger As ILogger(Of class_name)
  = _host.Services.GetRequiredService(Of ILogger(Of class_name))

public static class ServicesExtension
{
    public static ILoggingBuilder AddLog4NetNoDI(this ILoggingBuilder builder,
        IConfiguration config)
    {
        // We need to use a shared instance of the DataStore to pass to
        //  the LogViewerControl
        builder.Services.AddSingleton(MainControlsDataStore.DataStore);

        // call core Log4Net ServiceExtension initializer
        builder.AddLog4Net(config);

        return builder;
    }

    public static ILoggingBuilder AddLog4NetNoDI(this ILoggingBuilder builder,
        IConfiguration config, Action<DataStoreLoggerConfiguration> configure)
    {
        builder.AddLog4NetNoDI(config);
        builder.Services.Configure(configure);
        return builder;
    }
}

Public Module ServicesExtension

    <extension>
    Public Function AddLog4NetNoDI(builder As ILoggingBuilder,
        config As IConfiguration) As ILoggingBuilder

        ' We need to use a shared instance of the DataStore to pass to 
        '  the LogViewerControl
        builder.Services.AddSingleton(MainControlsDataStore.DataStore)

        ' call core Log4Net ServiceExtension initializer
        builder.AddLog4Net(config)

        Return builder

    End Function

    <extension>
    Public Function AddLog4NetNoDI(builder As ILoggingBuilder,
        config As IConfiguration, configure As Action(Of DataStoreLoggerConfiguration))
        As ILoggingBuilder

        builder.AddLog4NetNoDI(config)
        builder.Services.Configure(configure)
        Return builder

    End Function

End Module

public static class LoggingHelper
{
    #region Constructors

    static LoggingHelper()
    {
        // retrieve the log level from 'appsettings'
        string value = AppSettings<string>
            .Current("Logging:LogLevel", "Default") ?? "Information";
        Enum.TryParse(value, out LogLevel logLevel);

        IConfigurationRoot configuration = new ConfigurationBuilder()
            .Initialize()
            .Build();

        // wire up the loggers
        Factory = LoggerFactory.Create(builder => builder

            // visual debugging tools
            .AddLog4NetNoDI(configuration)

            // set minimum log level from 'appsettings*.json'
            .SetMinimumLevel(logLevel));
    }

    #endregion

    #region Properties

    public static ILoggerFactory Factory { get; }

    #endregion
}

Public Module LoggingHelper

#Region "Constructors"

	Sub New()

		' retrieve the log level from 'appsettings'
		Dim value As String = AppSettings(Of String) _
            .Current("Logging:LogLevel", "Default")

		If String.IsNullOrWhiteSpace(value) Then
			value = "Information"
		End If

		Dim logLevel As LogLevel
		If Not [Enum].TryParse(value, logLevel) Then
			logLevel = LogLevel.Information
		End If

		Dim configuration As IConfigurationRoot = New ConfigurationBuilder() _
			.Initialize() _
			.Build()

		' wire up the loggers
		Factory = LoggerFactory.Create(
			Sub(builder)

				builder.AddLog4NetNoDI(configuration)

				' set minimum log level from 'appsettings'
				builder.SetMinimumLevel(logLevel)

			End Sub)

	End Sub

#End Region

#Region "Properties"

	Public ReadOnly Property Factory As ILoggerFactory

#End Region

End Module

public static class LoggingHelper
{
    #region Constructors

    static LoggingHelper()
    {
        // retrieve the log level from 'appsettings'
        string value = AppSettings<string>
            .Current("Logging:LogLevel", "Default") ?? "Information";

        Enum.TryParse(value, out LogLevel logLevel);

        IConfigurationRoot configuration = new ConfigurationBuilder()
            .Initialize()
            .Build();

        // wire up the loggers
        Factory = LoggerFactory.Create(builder => builder

            // visual debugging tools
            .AddLog4NetNoDI(configuration, options =>
            {
                options.Colors[LogLevel.Trace] = new()
                {
                    Foreground = Color.White,
                    Background = Color.DarkGray
                };

                options.Colors[LogLevel.Debug] = new()
                {
                    Foreground = Color.White,
                    Background = Color.Gray
                };

                options.Colors[LogLevel.Information] = new()
                {
                    Foreground = Color.White,
                    Background = Color.DodgerBlue
                };

                options.Colors[LogLevel.Warning] = new()
                {
                    Foreground = Color.White,
                    Background = Color.Orchid
                };
            })

            // set minimum log level from 'appsettings*.json'
            .SetMinimumLevel(logLevel));
    }

    #endregion

    #region Properties

    public static ILoggerFactory Factory { get; }

    #endregion
}

Public Module LoggingHelper

#Region "Constructors"

	Sub New()

		' retrieve the log level from 'appsettings'
		Dim value As String = AppSettings(Of String) _
            .Current("Logging:LogLevel", "Default")

		If String.IsNullOrWhiteSpace(value) Then
			value = "Information"
		End If

		Dim logLevel As LogLevel
		If Not [Enum].TryParse(value, logLevel) Then
			logLevel = LogLevel.Information
		End If

		Dim configuration As IConfigurationRoot = New ConfigurationBuilder() _
			.Initialize() _
			.Build()

		' wire up the loggers
		Factory = LoggerFactory.Create(
			Sub(builder)

				builder.AddLog4NetNoDI(
					configuration,
					Sub(options)

						options.Colors(LogLevel.Trace) = New LogEntryColor() With
						{
							.Foreground = Color.White,
							.Background = Color.DarkGray
						}

						options.Colors(LogLevel.Debug) = New LogEntryColor() With
						{
							.Foreground = Color.White,
							.Background = Color.Gray
						}

						options.Colors(LogLevel.Information) = New LogEntryColor() With
						{
							.Foreground = Color.White,
							.Background = Color.DodgerBlue
						}

						options.Colors(LogLevel.Warning) = New LogEntryColor() With
						{
							.Foreground = Color.White,
							.Background = Color.Orchid
						}

					End Sub)

				' set minimum log level from 'appsettings'
				builder.SetMinimumLevel(logLevel)

			End Sub)

	End Sub

#End Region

#Region "Properties"

	Public ReadOnly Property Factory As ILoggerFactory

#End Region

End Module

Logger<class> logger
    = new Logger<class>(LoggingHelper.Factory);

Dim logger As Logger(Of class_name)
  = New Logger(Of class_name)(LoggingHelper.Factory)

RandomLoggingService service
    = new(new Logger<RandomLoggingService>(LoggingHelper.Factory));

Dim service As RandomLoggingService
  = New RandomLoggingService(New Logger(Of RandomLoggingService)(LoggingHelper.Factory))

public class MyConsumer
{
    #region Constructors 

    public MyConsumer(ILogDataStore dataStore)
        => _dataStore = dataStore;

    #endregion

    #region Properties

    private ILogDataStore? _dataStore;

    #endregion
}

Public Class MyConsumer

#Region "Constructors"

 Public Sub New(dataStore As ILogDataStore)

  _dataStore = dataStore

 End Sub

#End Region

#Region "Fields"

 Private _dataStore As ILogDataStore

#End Region

End Class

public class MyConsumer
{
    #region Constructors

    public MyConsumer(IServiceProvider serviceProvider)
        => _dataStore = serviceProvider.GetRequiredService<LogDataStore>();

   #endregion

    #region Properties

    private ILogDataStore? _dataStore;

    #endregion
}

Public Class MyConsumer

#Region "Constructors"

 Public Sub New(serviceProvider As IServiceProvider)

  _dataStore = serviceProvider.GetRequiredService(Of LogDataStore)

 End Sub

#End Region

#Region "Fields"

 Private _dataStore As ILogDataStore

#End Region

End Class

HostApplicationBuilder builder = Host.CreateApplicationBuilder();

builder.Services.AddSingleton<LogDataStore>(); // from `ServicesExtension` class above
builder.Services.AddTransient<MyConsumer>();

_host = builder.Build();

Dim builder As HostApplicationBuilder = Host.CreateApplicationBuilder()

builder.Services.AddSingleton(Of LogDataStore) ' from `ServicesExtension` class above
builder.Services.AddTransient(Of MyConsumer)

_host = builder.Build()

public static class MainControlsDataStore
{
    public static ILogDataStore DataStore { get; } = new();
}

Public Module MainControlsDataStore

 Public Property DataStore As ILogDataStore = New LogDataStore()

End Module

public class MyConsumer
{
    public MyConsumer(ILogDataStore dataStore)
        => _dataStore = dataStore;

    private LogDataStore? _dataStore;
}

Public Class MyConsumer

#Region "Constructors"

 Public Sub New(dataStore As ILogDataStore)

  _dataStore = dataStore

 End Sub

#End Region

#Region "Fields"

 Private _dataStore As ILogDataStore

#End Region

End Class

MyConsumer instance = new MyConsumer(MainControlsDataStore.DataStore);

Dim instance As MyConsumer = new MyConsumer(MainControlsDataStore.DataStore)

public class MyConsumer
{
    public MyConsumer(LogDataStore dataStore)
    {
        _dataStore = dataStore;
        _dataStore.Entries.CollectionChanged += OnCollectionChanged;
    }

    private ILogDataStore? _dataStore;

    private void OnCollectionChanged
            (object? sender, NotifyCollectionChangedEventArgs e)
    {
        // any new items?
        if (e.NewItems?.Count > 0)
        {
            // process new items
        }

        // any to remove? ... not required for this purpose.
        if (e.OldItems?.Count > 0)
        {
            // remove items
        }
    }
}

Public Class MyConsumer

#Region "Constructors"

 Public Sub New(ByVal dataStore As LogDataStore)
    _dataStore = dataStore
    _dataStore.Entries.CollectionChanged += AddressOf OnCollectionChanged
  End Sub

#End Region

#Region "Fields"

  Private _dataStore As ILogDataStore

#End Region

#Region "Methods"

  Private Sub OnCollectionChanged(sender As Object,
                                  e As NotifyCollectionChangedEventArgs)

    If e.NewItems?.Count > 0 Then
           ' process new items
    End If

    If e.OldItems?.Count > 0 Then
           ' remove items
    End If

  End Sub

#End Region

End Class

DispatcherHelper.Execute(() => delegate_method());

'DispatcherHelper
Execute(Sub() delegate_method())

DispatcherHelper.Execute(() =>
{
    // do work here
});

'DispatcherHelper
Execute(Sub()
   ' do work here
  End Sub)

await Dispatcher.UIThread.InvokeAsync(() => delegate_method());

Await Dispatcher.UIThread.InvokeAsync(Sub() delegate_method())

await Dispatcher.UIThread.InvokeAsync(() =>
{
    // do work here
});

Await Dispatcher.UIThread.InvokeAsync(
  Sub()
    ' do work here
  End Sub)

public static class DispatcherHelper
{
    public static void Execute(Action action)
    {
        // no cross-thread concerns
        if (Application.OpenForms.Count == 0)
        {
            action.Invoke();
            return;
        }

        try
        {
            if (Application.OpenForms[0]!.InvokeRequired)
                // Marshall to Main Thread
                Application.OpenForms[0]!.Invoke(action);
            else
                // We are already on the Main Thread
                action.Invoke();
        }
        catch (Exception)
        {
            // ignore as might be thrown on shutting down
        }
    }
}

Public Module DispatcherHelper

  Public Sub Execute(action As Action)

    ' no cross-tread concerns
    If Application.OpenForms.Count = 0 Then
      action.Invoke()
      Return
    End If

    Try

      If Application.OpenForms(0).InvokeRequired Then
        ' Marshall to Main Thread
        Application.OpenForms(0).Invoke(action)
      Else
        ' no cross-tread concerns
        action.Invoke()
      End If

    Catch ex As Exception

      ' ignore as might be thrown on shutting down

    End Try

  End Sub

End Module

public static class DispatcherHelper
{
    public static void Execute(Action action)
    {
        if (Application.Current is null || Application.Current.Dispatcher is null)
           // We are already on the Main Thread
           return;

        // Marshall to Main Thread
        Application.Current.Dispatcher.BeginInvoke
                    ( DispatcherPriority.Background, action);
    }
}

Public Module DispatcherHelper

  Public Sub Execute(action As Action)

    If Application.Current Is Nothing OrElse _
       Application.Current.Dispatcher Is Nothing Then
      Return
    End If

    ' Marshall to Main Thread
    Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Background, action)

  End Sub

End Module

public static class LoggerExtensions
{
    public static void Emit(this ILogger logger, EventId eventId,
        LogLevel logLevel, string message, Exception? exception = null,
        params object?[] args)
    {
        if (logger is null)
            return;

        //if (!logger.IsEnabled(logLevel))
        //    return;

        switch (logLevel)
        {
            case LogLevel.Trace:
                logger.LogTrace(eventId, message, args);
                break;

            case LogLevel.Debug:
                logger.LogDebug(eventId, message, args);
                break;

            case LogLevel.Information:
                logger.LogInformation(eventId, message, args);
                break;

            case LogLevel.Warning:
                logger.LogWarning(eventId, exception, message, args);
                break;

            case LogLevel.Error:
                logger.LogError(eventId, exception, message, args);
                break;

            case LogLevel.Critical:
                logger.LogCritical(eventId, exception, message, args);
                break;
        }
    }

    public static void TestPattern(this ILogger logger, EventId eventId)
    {
        Exception exception = new Exception("Test Error Message");

        logger.Emit(eventId, LogLevel.Trace, "Trace Test Pattern");
        logger.Emit(eventId, LogLevel.Debug, "Debug Test Pattern");
        logger.Emit(eventId, LogLevel.Information, "Information Test Pattern");
        logger.Emit(eventId, LogLevel.Warning, "Warning Test Pattern");
        logger.Emit(eventId, LogLevel.Error, "Error Test Pattern", exception);
        logger.Emit(eventId, LogLevel.Critical, "Critical Test Pattern", exception);
    }
}

Public Module LoggerExtensions

  ' NOTE Optional And ParamArray are not allowed in same method call,
  ' so used overload instead

  <Extension>
  Sub Emit(logger As ILogger, eventId As EventId,
      logLevel As LogLevel, message As String, ParamArray args As Object())
    logger.Emit(eventId, logLevel, message, Nothing, args)
  End Sub

  <Extension>
  Sub Emit(logger As ILogger, eventId As EventId,
    logLevel As LogLevel, message As String, [exception] As Exception,
    ParamArray args As Object())

    If logger Is Nothing Then
      Return
    End If

    If Not logger.IsEnabled(logLevel) Then
      Return
    End If

    Select Case logLevel
      Case LogLevel.Trace
        logger.LogTrace(eventId, message, args)

      Case LogLevel.Debug
        logger.LogDebug(eventId, message, args)

      Case LogLevel.Information
        logger.LogInformation(eventId, message, args)

      Case LogLevel.Warning
        logger.LogWarning(eventId, message, args)

      Case LogLevel.[Error]
        logger.LogError(eventId, [exception], message, args)

      Case LogLevel.Critical
        logger.LogCritical(eventId, message, args)

    End Select

  End Sub

  <Extension>
  Sub TestPattern(logger As ILogger, Optional eventId As EventId = Nothing)

    Dim exception As Exception = New Exception("Test Error Message")

    logger.Emit(eventId, LogLevel.Trace, "Trace Test Pattern")
    logger.Emit(eventId, LogLevel.Debug, "Debug Test Pattern")
    logger.Emit(eventId, LogLevel.Information, "Information Test Pattern")
    logger.Emit(eventId, LogLevel.Warning, "Warning Test Pattern")
    logger.Emit(eventId, LogLevel.Error, "Error Test Pattern", exception)
    logger.Emit(eventId, LogLevel.Critical, "Critical Test Pattern", exception)

  End Sub

End Module

public class LogViewerControlViewModel : ViewModel, ILogDataStoreImpl
{
    #region Constructor

    public LogViewerControlViewModel(ILogDataStore dataStore)
    {
        DataStore = dataStore;
    }

    #endregion

    #region Properties

    public ILogDataStore DataStore { get; set; }

    #endregion
}

Public Class LogViewerControlViewModel
   Inherits ViewModel
   Implements ILogDataStoreImpl

#Region "Constructors"

  Public Sub New(store As ILogDataStore)
    DataStore = store
  End Sub

#End Region

#Region "Properties"

  Public ReadOnly Property DataStore As ILogDataStore _
       Implements ILogDataStoreImpl.DataStore

#End Region

End Class

public partial class LogViewerControl : UserControl
{
    #region Constructors

    // supports DI and non-DI usage

    public LogViewerControl()
    {
        InitializeComponent();

        // Stop the flickering!
        ListView.SetDoubleBuffered();

        Disposed += OnDispose;
    }

    public LogViewerControl(LogViewerControlViewModel viewModel) : this()
        => RegisterLogDataStore(viewModel.DataStore);

    #endregion

    #region Fields

    private ILogDataStore? _dataStore;

    private static readonly SemaphoreSlim _semaphore = new(initialCount: 1);

    #endregion

    #region Methods

    public void RegisterLogDataStore(ILogDataStore dataStore)
    {
        _dataStore = dataStore;

        // As we are manually handling the DataBinding, we need to add existing
        //  log entries
        AddListViewItems(_dataStore.Entries);

        // Simple way to DataBind the ObservableCollection to the ListView is to
        //  listen to the CollectionChanged event
        _dataStore.Entries.CollectionChanged += OnCollectionChanged;
    }

    private void OnCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
    {
        // any new items?
        if (e.NewItems?.Count > 0)
        {
            AddListViewItems(e.NewItems.Cast<LogModel>());

            ExclusiveDispatcher(() =>
            {
                // auto-scroll if required
                if (CanAutoScroll.Checked)
                    ListView.Items[^1].EnsureVisible();
            });
        }

        // any to remove? ... not required for this purpose.
        if (e.OldItems?.Count > 0)
        {
            // remove from ListView.Items
        }
    }

    private void AddListViewItems(IEnumerable<LogModel> logEntries)
    {
        ExclusiveDispatcher(() =>
        {
            foreach (LogModel item in logEntries)
            {
                ListViewItem lvi = new ListViewItem
                {
                    Font = new(ListView.Font, FontStyle.Regular),
                    Text = item.Timestamp.ToString("G"),
                    ForeColor = item.Color!.Foreground,
                    BackColor = item.Color.Background
                };

                lvi.SubItems.Add(item.LogLevel.ToString());
                lvi.SubItems.Add(item.EventId.ToString());
                lvi.SubItems.Add(item.State?.ToString() ?? string.Empty);
                lvi.SubItems.Add(item.Exception ?? string.Empty);
                ListView.Items.Add(lvi);
            }
        });
    }

    private void ExclusiveDispatcher(Action action)
    {
        // ensure only one operation at time from multiple threads
        _semaphore.Wait();

        // delegate to UI thread
        DispatcherHelper.Execute(action.Invoke);

        _semaphore.Release();
    }

    // cleanup time ...
    private void OnDispose(object? sender, EventArgs e)
    {
        Disposed -= OnDispose;
        if (_dataStore is null)
            return;

        _dataStore.Entries.CollectionChanged -= OnCollectionChanged;
    }

    #endregion
}

Public Class LogViewerControl

#Region "Constructors"

  ' supports DI and non-DI usage

  Public Sub New()

    ' This call is required by the designer.
    InitializeComponent()

    ' Stop the flickering!
    ListView.SetDoubleBuffered()

    AddHandler Disposed, AddressOf OnDispose

  End Sub

  Public Sub New(viewModel As LogViewerControlViewModel)

    Me.New()

    RegisterLogDataStore(viewModel.DataStore)

  End Sub

#End Region

#Region "Fields"

  Private _dataStore As ILogDataStore

  Private Shared ReadOnly _semaphore As SemaphoreSlim =
    New SemaphoreSlim(initialCount:=1)

#End Region

#Region "Methods"

  Public Sub RegisterLogDataStore(datastore As ILogDataStore)

    _dataStore = datastore

    ' As we are manually handling the DataBinding, we need to add existing log entries
    AddListViewItems(_dataStore.Entries)

    ' Simple way to DataBind the ObservableCollection to the ListView Is to listen
    ' to the CollectionChanged event
    AddHandler _dataStore.Entries.CollectionChanged, AddressOf OnCollectionChanged

  End Sub

  Private Sub OnCollectionChanged(sender As Object, e As NotifyCollectionChangedEventArgs)

    ' any new items?
    If e.NewItems IsNot Nothing AndAlso e.NewItems.Count > 0 Then
      AddListViewItems(e.NewItems.Cast(Of LogModel))

      ExclusiveDispatcher(
        Sub()

          ' auto-scroll if required
          If CanAutoScroll.Checked Then
            ListView.Items(ListView.Items.Count - 1).EnsureVisible()
          End If

        End Sub)
    End If

    ' any to remove? ... not required for this purpose.
    If e.OldItems IsNot Nothing AndAlso e.OldItems.Count > 0 Then
      ' remove from ListView.Items
    End If

  End Sub

  Private Sub AddListViewItems(logEntries As IEnumerable(Of LogModel))


    ExclusiveDispatcher(
      Sub()

        For Each item As LogModel In logEntries
          Dim lvi As ListViewItem = New ListViewItem With
            {
              .Font = New Font(ListView.Font, FontStyle.Regular),
              .Text = item.Timestamp.ToString("G"),
              .ForeColor = item.Color.Foreground,
              .BackColor = item.Color.Background
            }

          lvi.SubItems.Add(item.LogLevel.ToString())
          lvi.SubItems.Add(item.EventId.ToString())
          lvi.SubItems.Add(If(item.State Is Nothing, String.Empty, item.State.ToString()))
          lvi.SubItems.Add(If(item.Exception Is Nothing, String.Empty,
                           item.Exception.ToString()))

          ListView.Items.Add(lvi)
        Next

      End Sub)

  End Sub

  Private Sub ExclusiveDispatcher(action As Action)

    ' ensure only one operation at time from multiple threads
    _semaphore.Wait()

    ' delegate to UI thread
    'DispatcherHelper.
    Execute(Sub() action.Invoke())

    _semaphore.Release()

  End Sub

  ' cleanup time ...
  Private Sub OnDispose(sender As Object, e As EventArgs)

    RemoveHandler Disposed, AddressOf OnDispose

    If _dataStore Is Nothing Then
      Return
    End If

    RemoveHandler _dataStore.Entries.CollectionChanged, AddressOf OnCollectionChanged

  End Sub

#End Region

End Class

public partial class LogViewerControl
{
    public LogViewerControl() => InitializeComponent();

    private void OnLayoutUpdated(object? sender, EventArgs e)
    {
        if (!CanAutoScroll.IsChecked == true)
            return;

        // design time
        if (DataContext is null)
            return;

        // Okay, we can now get the item and scroll into view
        LogModel? item = (DataContext as ILogDataStoreImpl)
                ?.DataStore.Entries.LastOrDefault();
        
        if (item is null)
            return;

        ListView.ScrollIntoView(item);
    }
}

Public Class LogViewerControl

  Public Sub New()

    ' This call is required by the designer.
    InitializeComponent()

  End Sub

  Private Sub OnLayoutUpdated(sender As Object, e As EventArgs)

    If Not CanAutoScroll.IsChecked Then
      Return
    End If

    ' design time
    If DataContext Is Nothing Then
      Return
    End If

    Dim store As ILogDataStoreImpl = DirectCast(DataContext, ILogDataStoreImpl)

    ' Okay, we can now get the item and scroll into view
    Dim item As LogModel = store.DataStore.Entries.LastOrDefault()

    If item Is Nothing Then
      Return
    End If

    ListView.ScrollIntoView(item)

  End Sub

End Class

public interface ILogDataStoreImpl
{
    public LogDataStore DataStore { get; }
}

Public Interface ILogDataStoreImpl

  ReadOnly Property DataStore As ILogDataStore

End Interface

public class ChangeColorTypeConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter,
                          CultureInfo culture)
    {
        SysDrawColor sysDrawColor = (SysDrawColor)value;
        return new SolidColorBrush(Color.FromArgb(
            sysDrawColor.A,
            sysDrawColor.R,
            sysDrawColor.G,
            sysDrawColor.B));
    }

    public object ConvertBack(object value, Type targetType, object parameter,
                              CultureInfo culture)
        => throw new NotImplementedException();
}

Public Class ChangeColorTypeConverter : Implements IValueConverter

  Public Function Convert(value As Object, targetType As Type,
                          parameter As Object, culture As CultureInfo)
                          As Object Implements IValueConverter.Convert

    Dim sysDrawColor As SysDrawColor = DirectCast(value, SysDrawColor)
    Return New SolidColorBrush(Color.FromArgb(
      sysDrawColor.A,
      sysDrawColor.R,
      sysDrawColor.G,
      sysDrawColor.B))

  End Function

  Public Function ConvertBack(value As Object, targetType As Type,
                              parameter As Object, culture As CultureInfo)
                              As Object Implements IValueConverter.ConvertBack
    Throw New NotImplementedException
  End Function

End Class

public partial class LogViewerControl : UserControl
{
    public LogViewerControl()
        => InitializeComponent();

    private ILogDataStoreImpl? vm;
    private LogModel? item;
  
    private void OnDataContextChanged(object? sender, EventArgs e)
    {
        if (DataContext is null)
            return;

        vm = (ILogDataStoreImpl)DataContext;
        vm.DataStore.Entries.CollectionChanged += OnCollectionChanged;
    }

    private void OnCollectionChanged
            (object? sender, NotifyCollectionChangedEventArgs e)
        => item = MyDataGrid.Items.Cast<LogModel>().LastOrDefault();

    private void OnLayoutUpdated(object? sender, EventArgs e)
    {
        if (CanAutoScroll.IsChecked != true || item is null)
            return;

        MyDataGrid.ScrollIntoView(item, null);
        item = null;
    }

    private void OnDetachedFromLogicalTree(object? sender, 
                 LogicalTreeAttachmentEventArgs e)
    {
        if (vm is null) return;
        vm.DataStore.Entries.CollectionChanged -= OnCollectionChanged;
    }
}

Partial Public Class LogViewerControl : Inherits UserControl

  Private _vm As ILogDataStoreImpl
  Private _model As LogModel

  Private MyDataGrid As DataGrid
  Private CanAutoScroll As CheckBox

  Sub New()
    InitializeComponent()
  End Sub

  ' Auto-wiring does not work for VB, so do it manually
  ' Wires up the controls and optionally loads XAML markup and attaches
  ' dev tools (if Avalonia.Diagnostics package is referenced)
  Private Sub InitializeComponent(Optional loadXaml As Boolean = True)

    If loadXaml Then
      AvaloniaXamlLoader.Load(Me)
    End If

    MyDataGrid = FindNameScope().Find("MyDataGrid")
    CanAutoScroll = FindNameScope().Find("CanAutoScroll")

  End Sub

  Private Shadows Sub OnDataContextChanged(sender As Object, e As EventArgs)

    If DataContext Is Nothing Then
      Return
    End If

    _vm = DirectCast(DataContext, ILogDataStoreImpl)
    AddHandler _vm.DataStore.Entries.CollectionChanged, 
               AddressOf OnCollectionChanged


  End Sub

  Private Sub OnCollectionChanged(sender As Object,
                                  e As NotifyCollectionChangedEventArgs)

    _model = MyDataGrid.Items.Cast(Of LogModel).LastOrDefault()

  End Sub

  Private Sub OnLayoutUpdated(sender As Object, e As EventArgs)

    If CanAutoScroll.IsChecked <> True OrElse _model Is Nothing Then
      Return
    End If

    MyDataGrid.ScrollIntoView(_model, Nothing)
    _model = Nothing

  End Sub

  Private Shadows Sub OnDetachedFromLogicalTree(sender As Object,
                                                e As LogicalTreeAttachmentEventArgs)

    If _vm Is Nothing Then
      Return
    End If

    RemoveHandler _vm.DataStore.Entries.CollectionChanged,
      AddressOf OnCollectionChanged

  End Sub

End Class

public interface ILogDataStoreImpl
{
    public LogDataStore DataStore { get; }
}

Public Interface ILogDataStoreImpl

  ReadOnly Property DataStore As ILogDataStore

End Interface

public class ChangeColorTypeConverter : IValueConverter
{
    public object Convert(object value, Type targetType,
                          object parameter, CultureInfo culture)
    {
        SysDrawColor sysDrawColor = (SysDrawColor)value;
        return new SolidColorBrush(Color.FromArgb(
            sysDrawColor.A,
            sysDrawColor.R,
            sysDrawColor.G,
            sysDrawColor.B));
    }

    public object ConvertBack(object value, Type targetType,
                              object parameter, CultureInfo culture)
        => throw new NotImplementedException();
}

Public Class ChangeColorTypeConverter : Implements IValueConverter

  Public Function Convert(value As Object, targetType As Type,
                          parameter As Object, culture As CultureInfo)
                          As Object Implements IValueConverter.Convert

    Dim sysDrawColor As SysDrawColor = DirectCast(value, SysDrawColor)
    Return New SolidColorBrush(Color.FromArgb(
      sysDrawColor.A,
      sysDrawColor.R,
      sysDrawColor.G,
      sysDrawColor.B))

  End Function

  Public Function ConvertBack(value As Object, targetType As Type,
                              parameter As Object, culture As CultureInfo)
                              As Object Implements IValueConverter.ConvertBack
    Throw New NotImplementedException
  End Function

End Class

public class EventIdConverter : IValueConverter
{
    public object Convert(object? value, Type targetType,
                          object? parameter, CultureInfo culture)
    {
        if (value is null)
            return "0";

        EventId eventId = (EventId)value;

        return eventId.ToString();
    }

    // If not implemented, an error is thrown
    public object ConvertBack(object? value, Type targetType, 
                              object? parameter, CultureInfo culture)
        => new EventId(0, value?.ToString() ?? string.Empty);
}

Public Class EventIdConverter : Implements IValueConverter

  Public Function Convert(value As Object, targetType As Type,
                          parameter As Object, culture As CultureInfo)
                          As Object Implements IValueConverter.Convert

    If value Is Nothing Then
      Return "0"
    End If

    Dim eventId As EventId = DirectCast(value, EventId)

    Return eventId.ToString()

  End Function

  Public Function ConvertBack(value As Object, targetType As Type,
                  parameter As Object, culture As CultureInfo)
                  As Object Implements IValueConverter.ConvertBack
    Return New EventId(0, If(value Is Nothing, String.Empty, value.ToString()))
  End Function

End Class

public static class ServicesExtension
{
    public static HostApplicationBuilder AddLogViewer(this HostApplicationBuilder builder)
    {
        builder.Services.AddSingleton<ILogDataStore, Logging.LogDataStore>();
        builder.Services.AddSingleton<LogViewerControlViewModel>();
        builder.Services.AddTransient<LogViewerControl>();

        return builder;
    }
}

Public Module ServicesExtension

  <Extension>
  Public Function AddLogViewer(builder As HostApplicationBuilder) _
         As HostApplicationBuilder

    builder.Services.AddSingleton(Of ILogDataStore, Logging.LogDataStore)
    builder.Services.AddSingleton(Of LogViewerControlViewModel)
    builder.Services.AddTransient(Of LogViewerControl)

    Return builder

  End Function

End Module

public partial class MainForm : Form
{
    #region Constructors

    public MainForm(MainControlsDataStore controlsDataStore)
    {
        InitializeComponent();

        // wire up the control
        HostPanel.AddControl(controlsDataStore.LogViewer);
    }

    #endregion
}

Public Class MainForm

#Region "Constructors"

  Sub New(controlsDataStore As MainControlsDataStore)

    ' This call is required by the designer.
    InitializeComponent()

    ' wire up the control
    HostPanel.AddControl(controlsDataStore.LogViewer)

  End Sub

#End Region

End Class

public static class ControlsExtension
{
    public static void AddControl(this Panel panel, Control control)
    {
        panel.Controls.Add(control);
        control.Dock = DockStyle.Fill;
        control.BringToFront();
    }
}

Public Module ControlsExtension

  <Extension>
  Public Sub AddControl(panel As Panel, control As Control)

    panel.Controls.Add(control)
    control.Dock = DockStyle.Fill
    control.BringToFront()

  End Sub

End Module

public partial class MainForm : Form
{
    public Form1()
    {
        InitializeComponent();

        // Initialize service and pass in the Logger
        RandomLoggingService service =
            new(new Logger<RandomLoggingService>(LoggingHelper.Factory));

        // Start generating log entries
        _ = service.StartAsync(CancellationToken.None);
        
        // manually wire up the logging to the view ...
        //   the control will show backlog entries...
        LogViewerControl.RegisterLogDataStore(MainControlsDataStore.DataStore);
    }
}

Public Class MyMainForm

  Sub New()

    ' This call is required by the designer.
    InitializeComponent()

    ' Initialize service and pass in the Logger
    Dim service As RandomLoggingService =
      New RandomLoggingService
      (New Logger(Of RandomLoggingService)(LoggingHelper.Factory))

    Dim task As Task = service.StartAsync(CancellationToken.None)

    ' manually wire up the logging to the view ...
    '   the control will show backlog entries...
    LogViewerControl.RegisterLogDataStore(MainControlsDataStore.DataStore)

  End Sub

End Class

public static class ServicesExtension
{
  public static HostApplicationBuilder AddLogViewer(this HostApplicationBuilder builder)
  {
    builder.Services.AddSingleton<ILogDataStore, Logging.LogDataStore>();
    builder.Services.AddSingleton<LogViewerControlViewModel>();
    builder.Services.AddTransient(service => new LogViewerControl
    {
      DataContext = service.GetRequiredService<LogViewerControlViewModel>()
    });

    return builder;
  }
}

Public Module ServicesExtension

  <Extension>
  Public Function AddLogViewer(builder As HostApplicationBuilder, _
  Optional config As Action(Of DataStoreLoggerConfiguration) = Nothing) _
  As HostApplicationBuilder

    builder.Services.AddSingleton(Of ILogDataStore, Logging.LogDataStore)
    builder.Services.AddSingleton(Of LogViewerControlViewModel)
    builder.Services.AddTransient(
      Function(service) New LogViewerControl() With
      {
        .DataContext = service.GetRequiredService(Of LogViewerControlViewModel)
      })

    Return builder

  End Function

End Module

public class MainViewModel : ViewModel
{
    #region Constructor

    public MainViewModel(LogViewerControlViewModel logViewer)
    {
        LogViewer = logViewer;
    }

    #endregion

    #region Properties

    public LogViewerControlViewModel LogViewer { get; }

    #endregion
}

Public Class MainViewModel : Inherits Viewmodel

#Region "Constructor"

  Public Sub New(logViewer As LogViewerControlViewModel)
    Me.LogViewer = logViewer
  End Sub

#End Region

#Region "Properties"

  Public Property LogViewer As LogViewerControlViewModel

#End Region

End Class

HostApplicationBuilder builder = Host.CreateApplicationBuilder();

builder.Logging.AddDataStoreLogger();

builder.Services.
    .AddSingleton<MainViewModel>()
    .AddSingleton<MainWindow>(service => new MainWindow
    {
        DataContext = service.GetRequiredService<MainViewModel>()
    });

_host = builder.Build();

Dim builder As HostApplicationBuilder = Host.CreateApplicationBuilder()

builder.Logging.AddDefaultDataStoreLogger()

Dim services As IServiceCollection = builder.Services

services _
  .AddSingleton(Of MainViewModel) _
  .AddSingleton(Of MainWindow)(
    Function(service) New MainWindow() With
    {
      .DataContext = service.GetRequiredService(Of MainViewModel)
    })

_host = builder.Build()

MainWindow = _host.Services.GetRequiredService<MainWindow>();
MainWindow.Show();

MainWindow = _host.Services.GetRequiredService(Of MainWindow)()
MainWindow.Show()

public partial class MainWindow : ILogDataStoreImpl
{
    public MainWindow()
    {
        InitializeComponent();

        // Initialize service and pass in the Logger
        RandomLoggingService service =
          new(new Logger<RandomLoggingService>(LoggingHelper.Factory));

        // Start generating log entries
        _ = service.StartAsync(CancellationToken.None);
        
        // manually wire up the logging to the view ...
        //   the control will show backlog entries...
        DataStore = MainControlsDataStore.DataStore;

        // we can't bind the controls' DataContext to a static object, so assign
        //   the DataStore to the Window and pass a reference to the Window itself
        LogViewerControl.DataContext = this;
    }

    // Passed to the LogViewerControl via the DataContext property as ILogDataStoreImpl
    public ILogDataStore DataStore { get; init;  }
}

Class MainWindow : Implements ILogDataStoreImpl

  Sub New()

    ' This call is required by the designer.
    InitializeComponent()

    ' Initialize service and pass in the Logger
    Dim service As RandomLoggingService =
      New RandomLoggingService(New Logger_
          (Of RandomLoggingService)(LoggingHelper.Factory))

    ' Start generating log entries
    Dim task As Task = service.StartAsync(CancellationToken.None)

    ' manually wire up the logging to the view ...
    '   the control will show backlog entries...
    DataStore = MainControlsDataStore.DataStore

    ' we can't bind the controls' DataContext to a static object, so assign
    '   the DataStore to the Window and pass a reference to the Window itself
    LogViewerControl.DataContext = Me

  End Sub

  Public Property DataStore As ILogDataStore Implements ILogDataStoreImpl.DataStore

End Class

public static class ServicesExtension
{
    public static HostApplicationBuilder AddLogViewer
                  (this HostApplicationBuilder builder)
    {
        builder.Services.AddSingleton<ILogDataStore, LogDataStore>();
        builder.Services.AddSingleton<LogViewerControlViewModel>();

        return builder;
    }
}

Public Module ServicesExtension

  <Extension>
  Public Function AddLogViewer(builder As HostApplicationBuilder,
                               Optional config As Action(Of DataStoreLoggerConfiguration)
                               = Nothing) As HostApplicationBuilder

    builder.Services.AddSingleton(Of ILogDataStore, Logging.LogDataStore)
    builder.Services.AddSingleton(Of LogViewerControlViewModel)

    Return builder

  End Function

End Module

public class MainViewModel : ViewModelBase
{
    #region Constructor

    public MainViewModel(LogViewerControlViewModel logViewer)
    {
        LogViewer = logViewer;
    }

    #endregion

    #region Properties

    public LogViewerControlViewModel LogViewer { get; }

    #endregion
}

Public Class MainViewModel : Inherits ViewModelBase

#Region "Constructor"

  Public Sub New(logViewer As LogViewerControlViewModel)
    Me.LogViewer = logViewer
  End Sub

#End Region

#Region "Properties"

  Public Property LogViewer As LogViewerControlViewModel

#End Region

End Class

HostApplicationBuilder builder = Host.CreateApplicationBuilder();

builder.Logging.AddDefaultDataStoreLogger();

builder.Services.
    .AddSingleton<MainViewModel>()
 .AddSingleton<MainViewModel>()
    .AddSingleton<MainWindow>(service => new MainWindow
    {
        DataContext = service.GetRequiredService<MainViewModel>()
    });

_host = builder.Build();

Dim builder As HostApplicationBuilder = Host.CreateApplicationBuilder()

builder.Logging.AddDefaultDataStoreLogger()

Dim services As IServiceCollection = builder.Services

services _
.AddSingleton(Of MainViewModel) _
.AddSingleton(Of MainWindow)(
  Function(service) New MainWindow() With
  {
    .DataContext = service.GetService(Of MainViewModel)
  })

_host = builder.Build()

desktop.MainWindow = _host.Services.GetRequiredService<MainWindow>();

desktop.MainWindow = _host.Services.GetRequiredService(Of MainWindow)

public partial class MainWindow : ILogDataStoreImpl
{
    public MainWindow()
    {
        InitializeComponent();

        // bare minimum to get the service running and wire up logging

        // Initialize service and pass in the Logger
        RandomLoggingService service =
            new(new Logger<RandomLoggingService>(LoggingHelper.Factory));

        // Start generating log entries
        _ = service.StartAsync(CancellationToken.None);
        
        // manually wire up the logging to the view ...
        //   the control will show backlog entries...
        DataStore = MainControlsDataStore.DataStore;

        // we can't bind the controls' DataContext to a static object, so assign
        //   the DataStore to the Window and pass a reference to the Window itself
        LogViewerControl.DataContext = this;
    }

    // Passed to the LogViewerControl via the DataContext property as ILogDataStoreImpl
    public LogDataStore DataStore { get; init;  }
}

Partial Public Class MainWindow : Inherits Window : Implements ILogDataStoreImpl

  Private LogViewerControl As LogViewerControl

  Sub New()

    ' This call is required by the designer.
    InitializeComponent()

    ' Initialize service and pass in the Logger
    Dim service As RandomLoggingService =
      New RandomLoggingService_
      (New Logger(Of RandomLoggingService)(LoggingHelper.Factory))

    ' Start generating log entries
    Dim task As Task = service.StartAsync(CancellationToken.None)

    ' manually wire up the logging to the view ...
    '   the control will show backlog entries...
    DataStore = MainControlsDataStore.DataStore

    ' we can't bind the controls' DataContext to a static object, so assign
    ' the DataStore to the Window and pass a reference to the Window itself
    LogViewerControl.DataContext = Me

  End Sub

  ' Auto-wiring does not work for VB, so do it manually
  ' Wires up the controls and optionally loads XAML markup and attaches
  '   dev tools (if Avalonia.Diagnostics package is referenced)
  Private Sub InitializeComponent(Optional loadXaml As Boolean = True)

    If loadXaml Then
      AvaloniaXamlLoader.Load(Me)
    End If

    LogViewerControl = FindNameScope().Find("LogViewerControl")

  End Sub

  Public Property DataStore As ILogDataStore Implements ILogDataStoreImpl.DataStore

End Class

public class RandomLoggingService : BackgroundService
{
    #region Constructors

    public RandomLoggingService(ILogger<RandomLoggingService> logger)
        => _logger = logger;

    #endregion

    #region Fields

    #region Injected

    private readonly ILogger _logger;

    #endregion

    // ChatGPT generated lists

    private readonly List<string> _messages = new()
    {
        "Bringing your virtual world to life!",
        // trimmed
    };

    readonly List<string> _eventNames = new()
    {
        "OnButtonClicked",
        // trimmed
    };

    readonly List<string> _errorMessages = new()
    {
        "Error: Could not connect to the server. Please check your internet connection.",
        // trimmed
    };

    private readonly Random _random = new();
    private static readonly EventId EventId = 
            new(id: 0x1A4, name: "RandomLoggingService");

    #endregion

    #region BackgroundService

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        _logger.Emit(EventId, LogLevel.Information, "Started");

        while (!stoppingToken.IsCancellationRequested)
        {
            // wait for a pre-determined interval
            await Task.Delay(1000, stoppingToken).ConfigureAwait(false);
            
            if (stoppingToken.IsCancellationRequested)
                return;

            // heartbeat logging
            GenerateLogEntry();
        }
  
        _logger.Emit(EventId, LogLevel.Information, "Stopped");
    }

    public Task StartAsync()
        => StartAsync(CancellationToken.None);

    public override async Task StartAsync(CancellationToken cancellationToken)
    {
        await Task.Yield();

        _logger.Emit(EventId, LogLevel.Information, "Starting");

        await base.StartAsync(cancellationToken).ConfigureAwait(false);
    }

    public Task StopAsync()
        => StopAsync(CancellationToken.None);

    public override async Task StopAsync(CancellationToken cancellationToken)
    {
        _logger.Emit(EventId, LogLevel.Information, "Stopping");
        await base.StopAsync(cancellationToken).ConfigureAwait(false);
    }

    #endregion

    #region Methods

    private void GenerateLogEntry()
    {
        LogLevel level = _random.Next(0, 100) switch
        {
            < 50 => LogLevel.Information,
            < 65 => LogLevel.Debug,
            < 75 => LogLevel.Trace,
            < 85 => LogLevel.Warning,
            < 95 => LogLevel.Error,
            _ => LogLevel.Critical
        };

        if (level < LogLevel.Error)
        {
            _logger.Emit(GenerateEventId(), level, GetMessage());
            return;
        }

        _logger.Emit(GenerateEventId(), level, GetMessage(),
            new Exception(_errorMessages[_random.Next(0, _errorMessages.Count)]));
    }

    private EventId GenerateEventId()
    {
        int index = _random.Next(0, _eventNames.Count);
        return new EventId(id: 0x1A4 + index, name: _eventNames[index]);
    }

    private string GetMessage()
        => _messages[_random.Next(0, _messages.Count)];

    #endregion
}

Public Class RandomLoggingService : Inherits BackgroundService

#Region "Constructors"

  Public Sub New(logger As ILogger(Of RandomLoggingService))

    _logger = logger

  End Sub

#End Region

#Region "Fields"

#Region "Injects"

  Private _logger As ILogger

#End Region

  ' ChatGPT generated lists

  Private ReadOnly _messages As List(Of String) = New List(Of String) From {
    "Bringing your virtual world to life!",
    ' trimmed
  }

  Private ReadOnly _eventNames As List(Of String) = New List(Of String)() From {
      "OnButtonClicked",
      ' trimmed
  }

  Private ReadOnly _errorMessages As List(Of String) = New List(Of String)() From {
      "Error: Could not connect to the server. Please check your internet connection.",
      ' trimmed
  }

  Private ReadOnly _random As Random = New Random()
  Private Shared ReadOnly EventId As EventId
    = New EventId(id:=&H1A4, name:="RandomLoggingService")

#End Region

#Region "BackgroundService"

  Protected Overrides Async Function ExecuteAsync(
    stoppingToken As CancellationToken) As Task

    _logger.Emit(EventId, LogLevel.Information, "Started")

    While Not stoppingToken.IsCancellationRequested

      ' wait for a pre-determined interval
      Await Task.Delay(1000, stoppingToken).ConfigureAwait(False)

      ' heartbeat logging
      GenerateLogEntry()

    End While

    _logger.Emit(EventId, LogLevel.Information, "Stopped")

  End Function

  Public Overrides Async Function StartAsync(
    cancellationToken As CancellationToken) As Task

    Await Task.Yield()

    _logger.Emit(EventId, LogLevel.Information, "Starting")
    Await MyBase.StartAsync(cancellationToken).ConfigureAwait(False)

  End Function

  Public Overrides Async Function StopAsync(
    cancellationToken As CancellationToken) As Task

    _logger.Emit(EventId, LogLevel.Information, "Stopping")
    Await MyBase.StopAsync(cancellationToken).ConfigureAwait(False)

  End Function

#End Region

#Region "Methods"

  Private Sub GenerateLogEntry()

    Dim level As LogLevel

    Select Case _random.Next(0, 100)
      Case < 50 : level = LogLevel.Information
      Case < 65 : level = LogLevel.Debug
      Case < 75 : level = LogLevel.Trace
      Case < 85 : level = LogLevel.Warning
      Case < 95 : level = LogLevel.Error
      Case Else : level = LogLevel.Critical
    End Select

    If level < LogLevel.Error Then
      _logger.Emit(GenerateEventId(), level, GetMessage())
      Return
    End If

    _logger.Emit(GenerateEventId(), level, GetMessage(),
          New Exception(_errorMessages(_random.Next(0, _errorMessages.Count))))

  End Sub

  Private Function GenerateEventId() As EventId

    Dim index As Integer = _random.[Next](0, _eventNames.Count)
    Return New EventId(id:=&H1A4 + index, name:=_eventNames(index))

  End Function

  Private Function GetMessage() As String

    Return _messages(_random.[Next](0, _messages.Count))

  End Function

#End Region

End Class

public static class ServicesExtension
{
    public static HostApplicationBuilder AddRandomBackgroundService(
        this HostApplicationBuilder builder)
    {
        builder.Services.AddSingleton<RandomLoggingService>();
        builder.Services.AddHostedService(service
            => service.GetRequiredService<RandomLoggingService>());

        return builder;
    }
}

Public Module ServicesExtension

  <Extension>
  Public Function AddRandomBackgroundService(builder As HostApplicationBuilder)
    As HostApplicationBuilder

    builder.Services.AddSingleton(Of RandomLoggingService)
    builder.Services.AddHostedService(
      Function(service) service.GetRequiredService(Of RandomLoggingService))

    Return builder

  End Function

End Module

HostApplicationBuilder builder = Host.CreateApplicationBuilder();

// Register the Random Logging Service
builder.AddRandomBackgroundService();

_host = builder.Build();

// startup one or more registered background services
_ = _host.StartAsync(_cancellationTokenSource.Token);

Dim builder As HostApplicationBuilder = Host.CreateApplicationBuilder()

' Random Logging Service
builder.AddRandomBackgroundService()

_host = builder.Build()

' startup background services
Dim task As Task = _host.StartAsync(_cancellationTokenSource.Token)

// Initialize service and pass in the Logger
RandomLoggingService service = 
   new(new Logger<RandomLoggingService>(LoggingHelper.Factory));

// Start generating log entries
_ = service.StartAsync(_cancellationTokenSource.Token);

' Initialize service and pass in the Logger
Dim service As RandomLoggingService = New RandomLoggingService_
            (New Logger(Of RandomLoggingService)(LoggingHelper.Factory))

' startup background services
Dim task As Task = _host.StartAsync(_cancellationTokenSource.Token)