Edit

Share via

Troubleshooting: Log Listeners (Visual Basic)

  • Article

You can use the My.Application.Log and My.Log objects to log information about events that occur in your application.

To determine which log listeners receive those messages, see Walkthrough: Determining Where My.Application.Log Writes Information.

The Log object can use log filtering to limit the amount of information that it logs. If the filters are misconfigured, the logs might contain the wrong information. For more information about filtering, see Walkthrough: Filtering My.Application.Log Output.

However, if a log is configured incorrectly, you may need more information about its current configuration. You can get to this information through the log's advanced TraceSource property.

To determine the log listeners for the Log object in code

  1. Import the System.Diagnostics namespace at the beginning of the code file. For more information, see Imports Statement (.NET Namespace and Type).

    Imports System.Diagnostics

  2. Create a function that returns a string consisting of information for each of the log's listeners.

    Function GetListeners(ByVal listeners As TraceListenerCollection) As String
    Dim ret As String = ""
    For Each listener As TraceListener In listeners
        ret &= listener.Name
        Dim listenerType As Type = listener.GetType
        If listenerType Is GetType(DefaultTraceListener) Then
            Dim tmp As DefaultTraceListener =
                DirectCast(listener, DefaultTraceListener)
            ret &= ": Writes to the debug output."
        ElseIf listenerType Is GetType(Logging.FileLogTraceListener) Then
            Dim tmp As Logging.FileLogTraceListener =
                DirectCast(listener, Logging.FileLogTraceListener)
            ret &= ": Log filename: " & tmp.FullLogFileName
        ElseIf listenerType Is GetType(EventLogTraceListener) Then
            Dim tmp As EventLogTraceListener =
                DirectCast(listener, EventLogTraceListener)
            ret &= ": Event log name: " & tmp.EventLog.Log
        ElseIf listenerType Is GetType(XmlWriterTraceListener) Then
            Dim tmp As Diagnostics.XmlWriterTraceListener =
                DirectCast(listener, XmlWriterTraceListener)
            ret &= ": XML log"
        ElseIf listenerType Is GetType(ConsoleTraceListener) Then
            Dim tmp As ConsoleTraceListener =
                DirectCast(listener, ConsoleTraceListener)
            ret &= ": Console log"
        ElseIf listenerType Is GetType(DelimitedListTraceListener) Then
            Dim tmp As DelimitedListTraceListener =
                DirectCast(listener, DelimitedListTraceListener)
            ret &= ": Delimited log"
        Else
            ret &= ": Unhandled log type: " &
                listenerType.ToString
        End If
        ret &= vbCrLf
    Next

    Return ret
End Function

  3. Pass the collection of the log's trace listeners to the GetListeners function, and display the return value.

    Dim ListenerCollection As TraceListenerCollection
ListenerCollection = My.Application.Log.TraceSource.Listeners
Dim ListenersText As String = GetListeners(ListenerCollection)
MsgBox(ListenersText)

    For more information, see TraceSource.

See also