BufferedWebEventProvider Class

Imports System
Imports System.Text
Imports System.IO
Imports System.Web.Management
Imports System.Collections.Generic
Imports System.Collections.Specialized
Imports System.Web



' Implements a custom event provider. 

Public Class SampleBufferedWebEventProvider
   Inherits BufferedWebEventProvider

   ' The local path of the file where 
   ' to store event information. 
   Private logFilePath As String = String.Empty

   ' Holds custom information. 
   Private customInfo As StringBuilder

   Private fs As FileStream

    Private providerName, buffer, bufferModality As String 


   Public Sub New()
      ' Perform local initializations. 
      ' Path of local file where to store  
      ' event info. 
      ' Assure that the path works for you and 
      ' that the right permissions are set.
      logFilePath = "C:/test/log.doc" 

      ' Instantiate buffer to contain  
      ' local data.
      customInfo = New StringBuilder()
   End Sub 'New 


   Public Overrides Sub Flush()
      customInfo.AppendLine("Perform custom flush")
        StoreToFile(customInfo, _
        logFilePath, FileMode.Append)
   End Sub 'Flush

   ' Initializes the provider. 
    Public Overrides Sub Initialize(ByVal name As String, _
    ByVal config As NameValueCollection)
        MyBase.Initialize(name, config)

        ' Get the configuration information.
        providerName = name
        buffer = SampleUseBuffering.ToString()
        bufferModality = SampleBufferMode

        customInfo.AppendLine(String.Format( _
        "Provider name: {0}", providerName))
        customInfo.AppendLine(String.Format( _
        "Buffering: {0}", buffer))
        customInfo.AppendLine(String.Format( _
        "Buffering modality: {0}", bufferModality))
    End Sub 'Initialize


   Public ReadOnly Property SampleUseBuffering() As Boolean 
      Get 
         Return UseBuffering
      End Get 
    End Property 


   Public ReadOnly Property SampleBufferMode() As String 
      Get 
         Return BufferMode
      End Get 
    End Property 

   ' Processes the incoming events. 
    ' This method performs custom  
    ' processing and, if buffering is  
    ' enabled, it calls the base.ProcessEvent 
    ' to buffer the event information. 
    Public Overrides Sub ProcessEvent( _
    ByVal eventRaised As WebBaseEvent)

        If UseBuffering Then 
            ' Buffering enabled, call the base event to 
            ' buffer event information. 
            MyBase.ProcessEvent(eventRaised)
        Else 
            ' Buffering disabled, store the current event 
            ' now.
            customInfo.AppendLine("*** Buffering disabled ***")
            customInfo.AppendLine(eventRaised.ToString())
            ' Store the information in the specified file.
            StoreToFile(customInfo, _
            logFilePath, FileMode.Append)
        End If 
    End Sub 'ProcessEvent


    Private Function GetEvents( _
    ByVal flushInfo As WebEventBufferFlushInfo) _
    As WebBaseEventCollection
        Return flushInfo.Events
    End Function 'GetEvents


    Private Function GetEventsDiscardedSinceLastNotification( _
    ByVal flushInfo _
    As WebEventBufferFlushInfo) As Integer 
        Return flushInfo.EventsDiscardedSinceLastNotification
    End Function 'GetEventsDiscardedSinceLastNotification


    Private Function GetEventsInBuffer(ByVal flushInfo _
    As WebEventBufferFlushInfo) As Integer 
        Return flushInfo.EventsInBuffer
    End Function 'GetEventsInBuffer


    Private Function GetLastNotificationTime(ByVal flushInfo _
    As WebEventBufferFlushInfo) As DateTime
        Return flushInfo.LastNotificationUtc
    End Function 'GetLastNotificationTime


    Private Function GetNotificationSequence(ByVal flushInfo _
    As WebEventBufferFlushInfo) As Integer 
        Return flushInfo.NotificationSequence
    End Function 'GetNotificationSequence


    Private Function GetNotificationType(ByVal flushInfo _
    As WebEventBufferFlushInfo) _
    As EventNotificationType
        Return flushInfo.NotificationType
    End Function 'GetNotificationType


    ' Processes the messages that have been buffered. 
    ' It is called by the ASP.NET when the flushing of  
    ' the buffer is required according to the parameters  
    ' defined in the <bufferModes> element of the  
    ' <healthMonitoring> configuration section. 
    Public Overrides Sub ProcessEventFlush(ByVal flushInfo _
    As WebEventBufferFlushInfo)

        ' Customize event information to be sent to  
        ' the Windows Event Viewer Application Log.
        customInfo.AppendLine( _
        "SampleEventLogWebEventProvider buffer flush.")

        customInfo.AppendLine(String.Format( _
        "NotificationType: {0}", _
        GetNotificationType(flushInfo)))

        customInfo.AppendLine(String.Format( _
        "EventsInBuffer: {0}", _
        GetEventsInBuffer(flushInfo)))

        customInfo.AppendLine(String.Format( _
        "EventsDiscardedSinceLastNotification: {0}", _
GetEventsDiscardedSinceLastNotification( _
flushInfo)))

        ' Read each buffered event and send it to the 
        ' Application Log. 
        Dim eventRaised As WebBaseEvent
        For Each eventRaised In flushInfo.Events
            customInfo.AppendLine(eventRaised.ToString())
        Next eventRaised
        ' Store the information in the specified file.
        StoreToFile(customInfo, logFilePath, _
        FileMode.Append)
    End Sub 'ProcessEventFlush

    ' Performs standard shutdown. 
    Public Overrides Sub Shutdown()
        ' Here you need the code that performs 
        ' those tasks required before shutting  
        ' down the provider. 
        ' Flush the buffer, if needed.
        Flush()

    End Sub 'Shutdown

    ' Store event information in a local file. 
    Private Sub StoreToFile(ByVal [text] _
    As StringBuilder, ByVal filePath As String, _
    ByVal mode As FileMode)
        Dim writeBlock As Integer 
        Dim startIndex As Integer 

        Try

            writeBlock = 256
            startIndex = 0

            ' Open or create the local file  
            ' to store the event information.
            fs = New FileStream(filePath, mode, FileAccess.Write)

            ' Lock the file for writing.
            fs.Lock(startIndex, writeBlock)

            ' Create a stream writer 
            Dim writer As New StreamWriter(fs)

            ' Set the file pointer to the current  
            ' position to keep adding data to it.  
            ' If you want to rewrite the file use  
            ' the following statement instead. 
            ' writer.BaseStream.Seek (0, SeekOrigin.Begin);
            writer.BaseStream.Seek(0, SeekOrigin.Current)

            'If the file already exists it must not  
            ' be write protected otherwise   
            ' the following write operation  
            'fails silently.
            writer.Write([text].ToString())

            ' Update the underlying file
            writer.Flush()

            ' Unlock the file for other processes.
            fs.Unlock(startIndex, writeBlock)

            ' Close the stream writer and  
            'the underlying file     
            writer.Close()

            fs.Close()
        Catch e As Exception
            'Use this for debugging. 
            'Never dispaly it! 
            Dim ex As String = e.ToString()
            Throw New Exception( _
            "[SampleEventProvider] StoreToFile: exception.")
        End Try 
    End Sub 'StoreToFile
End Class 'SampleBufferedWebEventProvider