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Customizing the Loggers
Logging with different Appenders in Same
application
We can customize the log4net framework to a granular
level where we can log some specific logs to a separate source and rest to the
default source. For example, to log all exception from a specific business rules
engine(Demo.Math.Utillities
namespace below) to SQL server and rest of the logs to a text file we can
use the below configuration.
namespace
Demo.Math.Utillities
{
public class ArithmeticEngine
{
private static readonly
ILog log = LogManager.GetLogger(typeof(ArithmeticEngine));
public
ArithmeticEngine()
{
//
// TODO: Add
constructor logic here
//
}
public double Div(int n1,
int n2)
{
double result
= 0;
try
{
result = n1 / n2;
}
catch (Exception ex)
{
log.Fatal(ex.Message, ex);
}
return
result;
}
}
}
Configuration
<log4net>
<appender name="RollingFile" type="log4net.Appender.RollingFileAppender">
<file value="D:\Technicals\Log4Net\Logs\example.log"/>
<appendToFile value="true"/>
<maximumFileSize value="100KB"/>
<maxSizeRollBackups value="2"/>
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%level %thread %logger - %message%newline"/>
</layout>
</appender>
<appender name="AdoNetAppender_SqlServer"
type="log4net.Appender.AdoNetAppender">
<connectionType value="System.Data.SqlClient.SqlConnection, System.Data,
Version=1.0.3300.0, Culture=neutral,
PublicKeyToken=b77a5c561934e089"
/>
<connectionString value="Data
Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated
Security=True;User Instance=True"
/>
<commandText value="INSERT INTO Log
([Date],[Thread],[Level],[Logger],[Message]) VALUES (@log_date, @thread,
@log_level, @logger, @message)"
/>
<parameter>
<parameterName value="@log_date" />
<dbType value="DateTime" />
<layout type="log4net.Layout.PatternLayout" value="%date{yyyy'-'MM'-'dd
HH':'mm':'ss'.'fff}" />
</parameter>
<parameter>
<parameterName value="@thread" />
<dbType value="String" />
<size value="255" />
<layout type="log4net.Layout.PatternLayout" value="%thread" />
</parameter>
<parameter>
<parameterName value="@log_level"
/>
<dbType value="String" />
<size value="50" />
<layout type="log4net.Layout.PatternLayout" value="%level" />
</parameter>
<parameter>
<parameterName value="@logger" />
<dbType value="String" />
<size value="255" />
<layout type="log4net.Layout.PatternLayout" value="%logger" />
</parameter>
<parameter>
<parameterName value="@message" />
<dbType value="String" />
<size value="4000" />
<layout type="log4net.Layout.PatternLayout" value="%message" />
</parameter>
</appender>
<logger name="Demo.Math.Utillities.ArithmeticEngine">
<level value="DEBUG" />
<appender-ref ref="AdoNetAppender_SqlServer"/>
</logger>
<root>
<level value="ALL"/>
<appender-ref ref="RollingFile"/>
</root>
</log4net>
The settings will log the exception generated from
Demo.Math.Utillities namespace to SqlServer table. See below.
Apart from the SqlServer table, the exception message
will also be logged to text file because of logger’s inheritance. By default,
the loggers configured in an application will follow a hierarchy and will
inherit the properties from their parent logger. For example, every logger in an
application will inherit from root logger. Thus, the logger Demo.Math.Utillities
will inherit from root logger and hence the exception will also be logged to
both text file and Sql server with the above setting. Similarly, if there is a
logger defined in a class under Demo.Math namespace then the loggers defined in
Demo.Math.Utillities will inherit them. To prevent the duplicate logging, you
can set additivity property of a logger to false if you want to prevent it from
inheriting from their parent logger. In our example, to prevent the logging from
Demo.Math.Utillities
logger to text file you can set additivity=”false”. Something like below,
<logger name="Demo.Math.Utillities.ArithmeticEngine" additivity="false">
<level value="DEBUG" />
<appender-ref
ref="AdoNetAppender_SqlServer"/>
</logger>
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