The following code example shows how to derive from the WebEventProvider class to create a custom provider that writes the configured events to a local file for which appropriate access rights must be granted. This custom provider example is simple and its main intent is to give you as developer full control of its basic mechanisms. In a real-world scenario, you could use this provider and especially the example buffered provider available at BufferedWebEventProvider, as a preliminary probe into the behavior of an application. This can help you during the design stage to gain an understanding of the information available; then later you can direct this information to a more complex provider.
The following configuration file excerpt shows a healthMonitoring section configuration that enables ASP.NET to use the custom provider defined above to process all health-monitoring events.
<healthMonitoring
heartBeatInterval="0"
enabled="true">
<providers>
<add name="SampleWebEventProvider"
type="SamplesAspNet.SampleEventProvider,webeventprovider, Version=1.0.1773.33989, Culture=neutral, PublicKeyToken=cf85aa6c978d9dea, processorArchitecture=MSIL" />
</providers>
<rules>
<rule
name="Custom Event Provider"
eventName="All Events"
provider="SampleWebEventProvider"
profile="Default" />
</rules>
</healthMonitoring>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 SampleEventProvider
Inherits System.Web.Management.WebEventProvider
' The local path of the file where
' to store event information.
Private logFilePath As String
' The current number of buffered messages
Private msgCounter As Integer
' The max number of messages to buffere.
Private maxMsgNumber As Integer
' The message buffer.
' private System.Collections.Generic.Queue
Private msgBuffer _
As System.Collections.Generic.Queue( _
Of System.Web.Management.WebBaseEvent) = _
New System.Collections.Generic.Queue( _
Of System.Web.Management.WebBaseEvent)
' Initializes the provider.
Public Sub New()
' Initialize the local path of the file
' that holds event information.
logFilePath = "C:/test/log.doc"
' Clear the message buffer.
msgBuffer.Clear()
' Initialize the max number of messages
' to buffer.
maxMsgNumber = 10
End Sub 'New
' More custom initialization goes here.
' Flush the input buffer if required.
Public Overrides Sub Flush()
' Create a string builder to
' hold the event information.
Dim reData As New StringBuilder()
' Store custom information.
reData.Append( _
"SampleEventProvider processing." + _
Environment.NewLine)
reData.Append( _
"Flush done at: {0}" + _
DateTime.Now.TimeOfDay.ToString() + _
Environment.NewLine)
Dim e As WebBaseEvent
For Each e In msgBuffer
' Store event data.
reData.Append(e.ToString())
Next e
' Store the information in the specified file.
StoreToFile(reData, logFilePath, FileMode.Append)
' Reset the message counter.
msgCounter = 0
' Clear the buffer.
msgBuffer.Clear()
End Sub 'Flush
' Shutdown the provider.
Public Overrides Sub Shutdown()
Flush()
End Sub 'Shutdown
' Process the event that has been raised.
Public Overrides Sub ProcessEvent( _
ByVal raisedEvent As WebBaseEvent)
If msgCounter < maxMsgNumber Then
' Buffer the event information.
msgBuffer.Enqueue(raisedEvent)
' Increment the message counter.
msgCounter += 1
Else
' Flush the buffer.
Flush()
End If
End Sub 'ProcessEvent
' 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.
Dim fs As 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
Throw New Exception( _
"SampleEventProvider.StoreToFile: " + _
e.ToString())
End Try
End Sub 'StoreToFile
End Class 'SampleEventProvider
using System;
using System.Text;
using System.IO;
using System.Web.Management;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Web;
namespace SamplesAspNet
{
// Implements a custom event provider.
public class SampleEventProvider :
System.Web.Management.WebEventProvider
{
// The local path of the file where
// to store event information.
private string logFilePath;
// The current number of buffered messages
private int msgCounter;
// The max number of messages to buffere.
private int maxMsgNumber;
// The message buffer.
private System.Collections.Generic.Queue
<WebBaseEvent> msgBuffer =
new Queue<WebBaseEvent>();
// Initializes the provider.
public SampleEventProvider(): base()
{
// Initialize the local path of the file
// that holds event information.
logFilePath = "C:/test/log.doc";
// Clear the message buffer.
msgBuffer.Clear();
// Initialize the max number of messages
// to buffer.
maxMsgNumber = 10;
// More custom initialization goes here.
}
// Flush the input buffer if required.
public override void Flush()
{
// Create a string builder to
// hold the event information.
StringBuilder reData = new StringBuilder();
// Store custom information.
reData.Append("SampleEventProvider processing." +
Environment.NewLine);
reData.Append("Flush done at: {0}" +
DateTime.Now.TimeOfDay.ToString() +
Environment.NewLine);
foreach (WebBaseEvent e in msgBuffer)
{
// Store event data.
reData.Append(e.ToString());
}
// Store the information in the specified file.
StoreToFile(reData, logFilePath, FileMode.Append);
// Reset the message counter.
msgCounter = 0;
// Clear the buffer.
msgBuffer.Clear();
}
// Shutdown the provider.
public override void Shutdown()
{
Flush();
}
// Process the event that has been raised.
public override void ProcessEvent(WebBaseEvent raisedEvent)
{
if (msgCounter < maxMsgNumber)
{
// Buffer the event information.
msgBuffer.Enqueue(raisedEvent);
// Increment the message counter.
msgCounter += 1;
}
else
{
// Flush the buffer.
Flush();
}
}
// Store event information in a local file.
private void StoreToFile(StringBuilder text,
string filePath, FileMode mode)
{
int writeBlock;
int startIndex;
try
{
writeBlock = 256;
startIndex = 0;
// Open or create the local file
// to store the event information.
FileStream fs = new FileStream(filePath,
mode, FileAccess.Write);
// Lock the file for writing.
fs.Lock(startIndex, writeBlock);
// Create a stream writer
StreamWriter writer = 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 (Exception e)
{
throw new Exception(
"SampleEventProvider.StoreToFile: "
+ e.ToString());
}
}
}
}