BufferedWebEventProvider Class

Definition

Namespace:

System.Web.Management

Assembly:

System.Web.dll

Provides the base functionality for creating event providers that require buffering.

public ref class BufferedWebEventProvider abstract : System::Web::Management::WebEventProvider

public abstract class BufferedWebEventProvider : System.Web.Management.WebEventProvider

type BufferedWebEventProvider = class
    inherit WebEventProvider

Public MustInherit Class BufferedWebEventProvider
Inherits WebEventProvider

Inheritance

Object

ProviderBase

WebEventProvider

BufferedWebEventProvider

Derived

System.Web.Management.MailWebEventProvider

System.Web.Management.SqlWebEventProvider

Examples

The following code example shows how to derive from the BufferedWebEventProvider class to create a custom provider that writes the configured events to a local file for which appropriate access rights must be granted.

using System;
using System.Text;
using System.IO;
using System.Web.Management;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Web;

 namespace Samples.AspNet.Management
 {
    // Implements a custom event provider.
    public class SampleBufferedWebEventProvider :
        BufferedWebEventProvider
    {

        // The local path of the file where
        // to store event information.
        private string logFilePath = string.Empty;

        // Holds custom information.
        private StringBuilder customInfo;

        private FileStream fs;

        private string providerName, 
            buffer, bufferModality;

        public SampleBufferedWebEventProvider()
        {
            // 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();
        }


        public override void  Flush()
        {
            customInfo.AppendLine("Perform custom flush");
            StoreToFile(customInfo, logFilePath, FileMode.Append);
        }

        // Initializes the provider.
        public override void Initialize(string name,
         NameValueCollection config)
        {
            base.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));
        }

        public bool SampleUseBuffering
        {
            get { return UseBuffering; }
        }

        public string SampleBufferMode
        {
            get { return BufferMode; }
        }


        // 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 override void ProcessEvent(
            WebBaseEvent eventRaised)
        {

            if (UseBuffering)
            {
                // Buffering enabled, call the 
                // base event to buffer event information.
                base.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);
            }
        }

        private WebBaseEventCollection GetEvents(
            WebEventBufferFlushInfo flushInfo)
        {
            return flushInfo.Events;
        }


        private int GetEventsDiscardedSinceLastNotification(
            WebEventBufferFlushInfo flushInfo)
        {
            return flushInfo.EventsDiscardedSinceLastNotification;
        }


        private int GetEventsInBuffer(
            WebEventBufferFlushInfo flushInfo)
        {
            return flushInfo.EventsInBuffer;
        }


        private DateTime GetLastNotificationTime(
            WebEventBufferFlushInfo flushInfo)
        {
            return flushInfo.LastNotificationUtc;
        }

        
        private int GetNotificationSequence(
            WebEventBufferFlushInfo flushInfo)
        {
            return flushInfo.NotificationSequence;
        }


        private EventNotificationType GetNotificationType(
            WebEventBufferFlushInfo flushInfo)
        {
            return flushInfo.NotificationType;
        }



        // Processes the messages that have been buffered.
        // It is called by the ASP.NET when the flushing of 
        // the buffer is required.
        public override void ProcessEventFlush(
            WebEventBufferFlushInfo flushInfo)
        {

            // 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.
            foreach (WebBaseEvent eventRaised in flushInfo.Events)
                customInfo.AppendLine(eventRaised.ToString());

            // Store the information in the specified file.
            StoreToFile(customInfo, logFilePath, FileMode.Append);
        }

        // Performs standard shutdown.
        public override void Shutdown()
        {
            // Here you need the code that performs
            // those tasks required before shutting 
            // down the provider.

            // Flush the buffer, if needed.
            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.
                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)
            {
                // Use this for debugging.
                // Never dispaly it!
                string ex = e.ToString();
                throw new Exception(
                    "[SampleEventProvider] StoreToFile: exception." );
            }
        }
    }
}

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

    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

    ' 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

    ' 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
End Class

The following configuration file excerpt shows a healthMonitoring configuration section that enables ASP.NET to use the custom provider defined above to process all health-monitoring events.

<healthMonitoring    
  heartBeatInterval="0" enabled="true">  

  <bufferModes>  
    <add name ="Custom Notification"  
      maxBufferSize="10"  
      maxFlushSize="5"  
      urgentFlushThreshold="10"  
      regularFlushInterval="Infinite"  
      urgentFlushInterval="00:00:30"  
      maxBufferThreads="1"  
/>  
  </bufferModes>  

  <providers>  
    <clear/>  
    <add name="SampleBufferedWebEventProvider"   
      type="SamplesAspNet.SampleBufferedWebEventProvider, bufferedwebeventprovider, Version=1.0.1785.14700, Culture=neutral, PublicKeyToken=d31491bf33b55954, processorArchitecture=MSIL"   
      buffer="true"  
      bufferMode="Custom Notification"  
/>  
  </providers>  

  <profiles>  
    <add name="Custom"   
      minInstances="1"   
      maxLimit="Infinite"   
      minInterval="00:00:00" />  
  </profiles>  

  <rules>  
    <clear />  
      <add name="Custom Buffered Web Event Provider"   
        eventName="All Events"  
        provider="SampleBufferedWebEventProvider"   
        profile="Custom" />  
  </rules>  

</healthMonitoring>  

Remarks

ASP.NET health monitoring allows production and operations staff to manage deployed Web applications. The System.Web.Management namespace contains the health-event types responsible for packaging application health-status data and the provider types responsible for processing this data. It also contains supporting types that help during the management of health events.

If you want to customize the health-event processing, you can derive from the BufferedWebEventProvider class to create your own custom buffered provider.

Note

In most cases you will be able to use the ASP.NET health-monitoring types as implemented, and you will control the health-monitoring system by specifying values in the healthMonitoring configuration section. You can also derive from the health-monitoring types to create your own custom events and providers. For an example of creating a custom provider, see How to: Implement the Health Monitoring Custom Provider Example.

Constructors

BufferedWebEventProvider()

Initializes a new instance of the BufferedWebEventProvider class.

Properties

BufferMode	Gets a value indicating the buffering mode used by the provider.
Description	Gets a brief, friendly description suitable for display in administrative tools or other user interfaces (UIs). (Inherited from ProviderBase)
Name	Gets the friendly name used to refer to the provider during configuration. (Inherited from ProviderBase)
UseBuffering	Gets a value indicating whether the provider is in buffered mode.

Methods

Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
Flush()	Moves the events from the provider's buffer into the event log.
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetType()	Gets the Type of the current instance. (Inherited from Object)
Initialize(String, NameValueCollection)	Sets the initial values for this object.
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ProcessEvent(WebBaseEvent)	Processes the event passed to the provider.
ProcessEventFlush(WebEventBufferFlushInfo)	Processes the buffered events.
Shutdown()	Performs tasks associated with shutting down the provider.
ToString()	Returns a string that represents the current object. (Inherited from Object)

See also

• WebEventBufferFlushInfo
• Installing and Configuring ASP.NET Providers