Troubleshooting: Log Listeners (Visual Basic)

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 (Visual Basic).

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 (Visual Basic).

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 &= ": Unhandeled 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

Tasks

Walkthrough: Determining Where My.Application.Log Writes Information (Visual Basic)

Reference

Microsoft.VisualBasic.Logging.Log

Concepts

Working with Application Logs in Visual Basic