how do you control the level of a trace listener in the config file

Question

I'm trying to learn the built-in features of tracing. I can't figure out how to use the config to set the level (information, warn, error) that gets written to my listen.

I have the default app.config with it . In my code, I use Trace.TraceInformation() and Trace.TraceError.

All of the messages are written to my text file. I want to be able to change something in the app.config to make it record Info messages or just error messages.

Module1.vb

Sub Main(ByVal args() As String)
    Dim index As Integer = 0
    For Each arg As String In args
        Trace.TraceInformation(String.Format("Sub Main(): arg({1}) = {0}", arg, index))
        Trace.Flush()

        If arg.Split("=").Count = 2 Then
            If String.Compare(arg.Split("=")(0), "mode", True) = 0 Then _Mode = arg.Split("=")(1)
        End If

        index += 1
    Next
End Sub

app.config

    <sources>
        <!-- This section defines the logging configuration for My.Application.Log -->
        <source name="DefaultSource">
            <listeners>
                <add name="FileLog"/>
                <!-- Uncomment the below section to write to the Application Event Log -->
                <!--<add name="EventLog"/>-->
            </listeners>
        </source>
    </sources>
    <switches>
        <add name="DefaultSwitch" value="1" />

    </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="HealthSurvey Console"/> -->
    </sharedListeners>

</system.diagnostics>

Answer 1

I'm not a fan of answering your own questions, but I also don't like leaving questions without marking something as the answer. This is especially true when I found what I was looking for.

This link had the info I needed. I will summarize because it is pretty long. In the config, you add a listener. The key that I needed was using the <filter> for the listener. With it, I can deploy my application and then change the config to control the text written to the file. I could add another listener that had a different filter like maybe the eventlog.

Anyway, the key was <filter>. The attribute initializeData is set to the text from System.Diagnostics.SourceLevels enum.

• Information allows Information, Warning, and Error
• Warning allows Warning and Error
• Error allows Error only

app.config

<system.diagnostics>
  <trace autoflush="false" indentsize="1">
    <listeners>
      <add name="textListener"
           type="System.Diagnostics.TextWriterTraceListener"
           traceOutputOptions="None"
           initializeData="C:\Projects\TraceLogOutput.log">
        <filter 
           type="System.Diagnostics.EventTypeFilter"
           initializeData="Information"/>
      </add>
    <remove name="Default" />
  </listeners>
</trace>

module1.vb

Sub Main(ByVal args() As String)

    ' initializeData = Information only
    Trace.TraceInformation("Some Information message")
    Trace.Flush()

    ' initializeData = Information or Warning
    Trace.TraceWarning("Some Warning message")
    Trace.Flush()

    ' initializeData = Information, Warning or Error
    Trace.TraceError("Some Error message")
    Trace.Flush()

End Sub