Log4Net

Dave Mateer — Tue, 24 Aug 2010 02:21:27 GMT

http://logging.apache.org/log4net/index.html

Logging to the console in a console app: (thanks to http://www.beefycode.com/?tag=/log4net for the great examples)

static void Main(string[]
args)

{

log4net.Config.BasicConfigurator.Configure();

log4net.ILog log = log4net.LogManager.GetLogger(typeof(Program));



log.Debug("Hello World!");

log.Info("I'm a simple log4net tutorial.");

log.Warn("... better be careful ...");

log.Error("ruh-roh: an error occurred");

log.Fatal("OMG we're dooooooomed!");



Console.ReadLine(); 


}

Using app.config

<configuration>

<configSections>

<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,
log4net"/>

</configSections>



<log4net>

<appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender">

<layout type="log4net.Layout.SimpleLayout" />

</appender>



<root>

<level value="INFO" />

<appender-ref ref="ConsoleAppender" />

</root>

</log4net>

</configuration>

notice level is set to INFO only.

Appenders

An object that persists the log messages somewhere.

eg AdoNetAppender, ConsoleAppender, ColoredConsoleAppender, EventLogAppender, FileAppender (don’t use), RollingFileAppender, SmtpAppender

Layout

All the different options:

http://www.beefycode.com/post/Log4Net-Tutorial-pt-4-Layouts-and-Patterns.aspx

<layout type="log4net.Layout.PatternLayout">

<conversionPattern value="%line
%date %-5level %logger - %message%newline" />

</layout>

Real Life

class Program

{

private static log4net.ILog
Log = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);



static void Main(string[]
args)

{

log4net.Config.XmlConfigurator.Configure();

Log.Info("this is an info message");

MyClass.WriteLog();



Console.ReadLine();

} 


}



class MyClass

{

private static log4net.ILog
Log = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);



public static void WriteLog()

{

Log.Info("this is an info message");

}

}

Shows us which class called the logger.

Web Apps

Putting this in AssemblyInfo.cs

[assembly: log4net.Config.XmlConfigurator()]

Connection Strings and AdoNetAppender

bufferSize value=”1” – otherwise it won’t write each one seperatly

This proved hard

http://weblogs.asp.net/drnetjes/archive/2005/02/16/374780.aspx

doing a search and replace here didn’t work

Nor did extending the provider

http://stackoverflow.com/questions/2441359/can-you-pull-the-connectionstring-for-a-log4net-adonetappender-from-elsewhere-in

** this could be better: http://blog.dynamicprogrammer.com/CommentView,guid,357a3fbe-59e7-4dd4-846a-89083e903532.aspx

Recommended Practice in Code

http://www.beefycode.com/post/Log4Net-Recommended-Practices-pt-1-Your-Code.aspx

Whenever you catch an exception, log it.

Internal Log4Net Logging

When trying to figure out why somethings aren’t working (eg connection strings)

In web.config:

<add key="log4net.Internal.Debug" value="true" />

</appSettings>

<system.diagnostics>

<trace autoflush="true">

<listeners>

<add

name="textWriterTraceListener"


type="System.Diagnostics.TextWriterTraceListener"


initializeData="c:\\log4net.txt" />

</listeners>

</trace>

</system.diagnostics>

ProgramGood.Net - Log4Net

this.Log