public static void Write(object message)
public static void Write(object message, string category)
...
public static void Write(LogEntry log)

public interface ILogSink
{
    /// <summary>
    /// Send message to log sink handler.
    /// </summary>
    /// <param name="log">xmlMessage as string</param>
    void SendMessage(LogEntry log);

    /// <summary>
    /// Sets the formatter to be used by this sink.
    /// </summary>

    ILogFormatter Formatter { get; set; }
}

using System;
using System.Collections;

using Microsoft.Practices.EnterpriseLibrary.Logging;

public class GeneralLogEntry : LogEntry
{    
    public GeneralLogEntry(string message) : this(message, 2) {}
    
    public GeneralLogEntry(string message, int priority) : base()
    {
        Category = "General";
        Priority = priority;
        Severity = Severity.Unspecified;
        Message = message;
    }
}

public class ExceptionLogEntry : LogEntry
{    
    public ExceptionLogEntry(string message) : this(message, 5) {}
    
    public ExceptionLogEntry(string message, int priority) : base()
    {
        Category = "Exception";
        Priority = priority;
        Severity = Severity.Error;
        Message = message;
    }
}

public class PerformanceLogEntry : LogEntry
{
    public PerformanceLogEntry(string message) : this(message, 3) {}
    
    public PerformanceLogEntry(string message, int priority) : base()
    {
        Category = "Performance";
        Priority = priority;
        Severity = Severity.Information;
        Message = message;
    }
}

public class SecurityLogEntry : LogEntry
{
    public SecurityLogEntry(string message) : this(message, 5) {}
    
    public SecurityLogEntry(string message, int priority) : base()
    {
        Category = "Security";
        Priority = priority;
        Severity = Severity.Warning;
        Message = message;
    }
}

public class DebugLogEntry : LogEntry
{
    public DebugLogEntry(string message) : this(message, 1) {}
    
    public DebugLogEntry(string message, int priority) : base()
    {
        Category = "Debug";
        Priority = priority;
        Severity = Severity.Information;
        Message = message;
    }
}

public class MyClass
{
    public static void Main()
    {
        Logger.Write(new GeneralLogEntry("A Beautiful Day"));
        Logger.Write(new DebugLogEntry("Loading Array"));
        Logger.Write(new SecurityLogEntry("User is not authenticated."));
        Logger.Write(new PerformanceLogEntry("Application running slow...", 4));
        Logger.Write(new ExceptionLogEntry("Division by zero exception."));
    }
    
}

----------------------------------------
Timestamp: 3/16/2005 4:50:49 PM
Message: A Beautiful Day
Category: General
Priority: 2
Severity: Unspecified
----------------------------------------
Timestamp: 3/16/2005 4:50:50 PM
Message: Loading Array
Category: Debug
Priority: 1
Severity: Information
----------------------------------------
Timestamp: 3/16/2005 4:50:50 PM
Message: User is not authenticated.
Category: Security
Priority: 5
Severity: Warning
----------------------------------------
Timestamp: 3/16/2005 4:50:50 PM
Message: Application running slow...
Category: Performance
Priority: 4
Severity: Information
----------------------------------------
Timestamp: 3/16/2005 4:50:50 PM
Message: Division by zero exception.
Category: Exception
Priority: 5
Severity: Error

using System;
using System.Collections;

using Microsoft.Practices.EnterpriseLibrary.Logging;
    
public enum Priority : int
    { Low = 1, Medium = 3, High = 5 }
    
public sealed class Log
{
    public static void WriteGeneralEntry (string message, Priority priority)
    {
        Logger.Write(message, "General", (int)priority);
    }
    
    public static void WriteDebugEntry (string message, Priority priority)
    {
        Logger.Write(message, "Debug", (int)priority);
    }
}

public class MyClass
{
    public static void Main()
    {
        Log.WriteGeneralEntry("New Entry", Priority.Low);
        Log.WriteDebugEntry("Blog Down", Priority.High);
    }
    
}