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WebEventProvider Class

Provides the base class for non buffered event providers.

Namespace:  System.Web.Management
Assembly:  System.Web (in System.Web.dll)

[AspNetHostingPermissionAttribute(SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal)]
[AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
public abstract class WebEventProvider : ProviderBase

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 WebEventProvider class to create your own custom provider.

NoteNote:

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 deriving from the WebEventProvider class, see the example provided in this topic.

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>
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());
            }
        }

    }

}

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0

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