Best Practice logging pattern for Silverlight application

Copy/paste following code to NLog.Config. I am not going in deep of different sections of config. Detail can be found in NLog documentation.

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <!-- make sure to set 'Copy To Output Directory' option for this file -->
  <!-- go to http://nlog-project.org/wiki/Configuration_file for more information -->
    <targets>
    <!-- Log in a separate thread, possibly queueing up to
    5000 messages. When the queue overflows, discard any
    extra messages-->
        <target name="file" xsi:type="AsyncWrapper" queueLimit="5000" overflowAction="Discard">
            <target xsi:type="File" fileName="${basedir}/logs/${level}.txt" 
            layout="${longdate} ${logger} ${message}"
            archiveFileName="${basedir}/logs/archives/${level}.{#####}.txt"
            archiveAboveSize="10240"
            archiveNumbering="Sequence"
            concurrentWrites="true"
            keepFileOpen="false"
            encoding="iso-8859-2"/>
        </target>
    </targets>
<rules>
    <logger name="*" minlevel="Debug" writeTo="file" />
</rules>
</nlog>

In this configuration I have set asynchronous logging with log archieve.

Sort tag introduction: is as follows.

• <targets /> – defines log targets/outputs
• <rules /> – defines log routing rules
• <extensions /> – loads NLog extensions from the *.dll file
• <include /> – includes external configuration file
• <variable /> – sets the value of a configuration variable

Add following appsettings to web.config for switching on/off logging.

<appSettings>
    <add key="IsEventLogOn" value="true" /> 
</appSettings> 

I am going to add RIA service to receive log requests from Silverlight project.

Add empty RIA service ‘LoggingService.cs’ in Web project.

Write following methods in WCF RIA Service.

using NLog; //Add in namespace section
private static readonly Logger Logger = LogManager.GetLogger("LoggingService"); 
[Invoke]
public string GetLogONOFFFlag()
{
    string flag = ConfigurationManager.AppSettings.Get("IsEventLogOn");
    return flag;
}
protected override void OnError(DomainServiceErrorInfo errorInfo)
{
    //Log exception errorInfo.Error 
    LogException("Error in BriteDomainService RIA Service. ", errorInfo.ToString());
    base.OnError(errorInfo);
}
[Invoke]
public void LogException(string errorCommentOrType, string Detail)
{
    string errorMessage = String.Empty;
    string strUser = string.Empty;
    try
    {
    //Following code for getting user name will work only when ApplicationServices is set in connection string. I will cover it in next topic
    if (this.ServiceContext.User != null)
    if (this.ServiceContext.User.Identity != null)
    strUser = this.ServiceContext.User.Identity.Name;
    Detail = " [UserName: " + strUser + "] " + "Time: " + DateTime.Now.ToString() + " " + Detail;
    }
    catch (Exception ex)
    {
        Logger.Error("Logging Error: " + ex);
    }
    finally
    {
        errorMessage = errorCommentOrType + " - " + Detail;
        switch (errorCommentOrType)
        {
    case "Fatal":
        Logger.Fatal(errorMessage);
    break;
    case "Error":
        Logger.Error(errorMessage);
    break;
    case "Warn":
        Logger.Warn(errorMessage);
    break;
    case "Info":
        Logger.Info(errorMessage);
    break;
    case "Debug":
        Logger.Debug(errorMessage);
    break;
    case "Trace":
        Logger.Trace(errorMessage);
    break;
    default:
        Logger.Error(errorMessage);
    break;
}

public bool IsEventLogOn { get; set; } 

Write following lines to call RIA service to get ‘IsEventLogOn’ value inside ‘Application_UserLoaded’.

//Call RIA Service to get Log ON/OFF Flag
var context = new BusinessAppMVVM.Web.Services.LoggingContext();
context.GetLogONOFFFlag(GetLogONOFFFlagCompleted, null);

Add ‘LoggerManager’ class file in ‘Helpers’ folder. This class I am going to use to send errors to Logging service. Code can look like.

public class LoggerManager
{
/// <summary>
/// Writing the Error and Activity logs in the log files.
/// </summary>
/// <param name="errorCommentOrType">Error Comment or Error Type or in case of event enter Event Name</param>
/// <param name="errorDetails">Error Details</param>
/// <returns>bool</returns>
public static bool WriteLog(string errorCommentOrType, string errorDetails)
{
try
{
    MessageBox.Show("Some error is occured in application. Please try again after refresh. " + errorDetails);
    if (((App)Application.Current).IsEventLogOn)
    {
        LoggingContext logErrorServiceClient = new LoggingContext();
        logErrorServiceClient.LogException(errorCommentOrType, errorDetails,
        invokeOperation =>
        {
            if (invokeOperation.HasError)
            {
                MessageBox.Show("Some error is occurred while error logging!");
            }
            else
                MessageBox.Show(@"Error is logged in BusinessAppMVVM\BusinessAppMVVM.Web\logs\.");
        }, null);
    }
    return true;
}
catch (Exception ex)
{
    return false;
}
}
}
/// <summary>
/// Log Type
/// </summary>
public enum LogType
{
    DEBUG,
    ERROR,
    FATAL,
    INFO,
    WARN
}

As per log type log files are generating. So you can use it for debug information too. You have seen this logging process is configurable for on/off.

Run Application and click on button.