Application Logging

Some new classes were introduced to facilitate application logging. Previously, we had to depend on 3rd party libraries like log4net. One of the classes that are most useful is the FileLogTraceListener which provided autoarchiving by date or by application.

I started exploring the information using information from the this article.

First lets start with the app.config file:

<system.diagnostics>
        <sources>
            <!-- This section defines the logging configuration for My.Application.Log -->
          <source name="DefaultSource" switchName="MSwitch">
            <listeners>
              <add name="LogToFile" />
            </listeners>
          </source>
        </sources>
        <switches>
            <add name="MSwitch" value="All" />
        </switches>
        <sharedListeners>
            <add name="FileLog"
                 type="Microsoft.VisualBasic.Logging.FileLogTraceListener, Microsoft.VisualBasic, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" 
                 initializeData="FileLogWriter"/>
            <!-- Uncomment the below section and replace APPLICATION_NAME with the name of your application to write to the Application Event Log -->
            <!--<add name="EventLog" type="System.Diagnostics.EventLogTraceListener" initializeData="APPLICATION_NAME"/> -->
            <add name="LogToFile" type="Microsoft.VisualBasic.Logging.FileLogTraceListener, Microsoft.VisualBasic, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL"
            initializeData="FileLogWriter"
                   logFileCreationSchedule="Daily"
                   traceOutputOptions="DateTime"
                   BaseFileName="W_Test"
                   location="Custom"
                   CustomLocation="c:\log\"
                   Delimiter ="|"
                   AutoFlush="True"
                   Append="True"
            />
        </sharedListeners>
    </system.diagnostics>

To use be able to use My.Application.log class, you need a source called DefaultSource, you can then point it to a switch name. In the switch name (or place the value directly using SwitchValue, you have an option to identify the level of logging (taken from the help file) :

ActivityTracing Enumeration
Description
Off	Does not allow any events through.
Critical	Allows only Critical events through.
Error	Allows Critical and Error events through.
Warning	Allows Critical, Error, and Warning events through.
Information	Allows Critical, Error, Warning, and Information events through.
Verbose	Allows Critical, Error, Warning, Information, and Verbose events through.
ActivityTracing	Allows the Stop, Start, Suspend, Transfer, and Resume events through.
All	Allows all events through.

You can then add various listeners. If you are using FileLogTraceListener,

• you can specify the BaseFileName. This will be the used as your log file name.
  
• specify whether or not to append to the log.
• autoflush
• location (if specify Custom then specify CustomLocation to tell it where to put the file).
• logFileCreationSchedule whether to create Daily, Weekly or None.
• Delimiter (character to use as delimiter between the columns in the log file).
• TraceOutputOption (additional items to automatically add to the log file). If you use DateTime, it will provide it give you the time in GMT timezone.

Based on the above configuration, my log file will have the name W_Test-2008-05-24.log and the content will look something like this:

DefaultSource|Start|4|Entering Button2_click|2008-05-24 03:37:54Z
DefaultSource|Stop|5|Leaving Button2_click|2008-05-24 03:37:54Z
DefaultSource|Information|0|Going thru Button2|2008-05-24 03:37:54Z