Programming Windows Services with Microsoft Visual Basic 2008 : Services and Polling - Updating the Service Events

7/8/2013 9:12:19 PM

We want to use the new service events properly by modifying the current events. This will allow us to reuse these structured literals quickly.

Modifying Our <OnStart>

We will be modifying our current tutorials.vb thread function code to reflect both the changes in using our resource file and to use our new InstanceId constants.

Listing 1. Modifications to <OnStart> to support the new resource file.

Protected Overrides Sub OnStart(ByVal args() As String)
  ' Add code here to start your service. This method should set things
  ' in motion so your service can do its work.
  Try
    m_WorkerThread = New Thread(AddressOf ThreadFunc)
    m_WorkerThread.Name = My.Resources.ThreadName
    m_WorkerThread.Priority = ThreadPriority.Normal
    m_WorkerThread.Start()
    WriteLogEvent(My.Resources.ServiceStarting, ONSTART_INFO, _
    EventLogEntryType.Information, My.Resources.Source)
  Catch ex As Exception
    'We Catch the Exception
    'to avoid any unhandled errors
    'and we will stop the service if any occur here
    Me.Stop()
  End Try
End Sub

The listing shows that I am now using the My Object to read from the localization resource file.

Modifying <OnStop>

Now let’s update the <OnStop> method to reflect the use of Resources and WriteEventLog call changes. Listing 2 shows the changes.

Listing 2. Modifications to <OnStop> to support the new resource file.

Protected Overrides Sub OnStop()
' Add code here to perform any tear-down necessary to stop your service.
  Try
    If (Not m_WorkerThread Is Nothing) Then
        Try
            Me.RequestAdditionalTime(THIRTY_SECONDS)
            m_WorkerThread.Join(TIME_OUT)
            m_ThreadAction.StopThread = True
        Catch ex As Exception
        m_ThreadAction = Nothing
        End Try
    End If
    WriteLogEvent(My.Resources.ServiceStopping, ONSTOP_INFO, _
    EventLogEntryType.Information, My.Resources.Source)
  Catch ex As Exception
  End Try
End Sub

Modifying <OnPause>

As shown in Listing 3, you must once again update <OnPause>.

Listing 3. Modifications to <OnPause> to support the new resource file.

Protected Overrides Sub OnPause()
   Try
       m_ThreadAction.Pause = True
       WriteLogEvent(My.Resources.ServicePausing, ONPAUSE_INFO, _
       EventLogEntryType.Information, My.Resources.Source)
   Catch ex As Exception
    'We Catch the Exception
    'to avoid any unhandled errors
    'since we are pausing and
    'logging an event is what failed
    'we will merely write the output
    'to the debug window
    Debug.WriteLine("Error pausing service: " + ex.ToString())
    Me.Stop()
       'do nothing
   End Try
End Sub

Modifying <OnContinue>

Listing 4 shows how to update the <OnContinue> method.

Listing 4. Modifications to <OnContinue> to support the new resource file.

Protected Overrides Sub OnContinue()
   Try
       m_ThreadAction.Pause = False
       WriteLogEvent(My.Resources.ServiceContinuing, ONCONTINUE_INFO, _
       EventLogEntryType.Information, My.Resources.Source)
   Catch ex As Exception
    'We Catch the Exception
    'to avoid any unhandled errors
    'since we are resuming and
    'logging an event is what failed
    'we will merely write the output
    'to the debug window
    Debug.WriteLine("Error resuming service: " + ex.ToString())
    Me.Stop()
   End Try
End Sub