IWebEventCustomEvaluator Interface

Definition

Namespace:

System.Web.Management

Assembly:

System.Web.dll

Evaluates whether an event should be sent to the related provider for processing.

public interface class IWebEventCustomEvaluator

public interface IWebEventCustomEvaluator

type IWebEventCustomEvaluator = interface

Public Interface IWebEventCustomEvaluator

Examples

The following code example shows how to derive from the IWebEventCustomEvaluator interface when creating a custom event.

using System;
using System.Text;
using System.Web;
using System.Web.Management;

namespace SamplesAspNet
{
  // Implements a custom WebBaseEvent class. 
    public class SampleWebBaseEvent :
        System.Web.Management.WebBaseEvent, IWebEventCustomEvaluator
    {
        private string customCreatedMsg, customRaisedMsg;

        // Store firing record info.
        private static string firingRecordInfo;

        // Implements the IWebEventCustomEvaluator.CanFire 
        // method. It is called by the ASP.NET if this custom
        // type is configured in the profile
        // element of the healthMonitoring section.
        public bool CanFire(
            System.Web.Management.WebBaseEvent e, 
            RuleFiringRecord rule)
        {

            bool fireEvent;
            string lastFired = rule.LastFired.ToString();
            string timesRaised = rule.TimesRaised.ToString();

            // Fire every other event raised.
            fireEvent =
                (rule.TimesRaised % 2 == 0) ? true : false;

            if (fireEvent)
            {
                firingRecordInfo =
                    string.Format("Event last fired: {0}",
                    lastFired) +
                    string.Format(". Times raised: {0}",
                    timesRaised);
            }
            else
                firingRecordInfo =
                  string.Format(
                   "Event not fired. Times raised: {0}",
                   timesRaised);

            return fireEvent;
        }

        // Invoked in case of events identified only by 
        // their event code.
        public SampleWebBaseEvent(string msg, 
            object eventSource, int eventCode):
          base(msg, eventSource, eventCode)
        {
            // Perform custom initialization.
            customCreatedMsg =
            string.Format("Event created at: {0}",
            EventTime.ToString());
        }

        // Invoked in case of events identified by their 
        // event code.and related event detailed code.
        public SampleWebBaseEvent(string msg, object eventSource, 
            int eventCode, int eventDetailCode):
          base(msg, eventSource, eventCode, eventDetailCode)
        {
            // Perform custom initialization.
            customCreatedMsg =
             string.Format("Event created at: {0}",
             EventTime.ToString());
        }


        // Raises the SampleWebBaseEvent.
        public override void Raise()
        {
            // Perform custom processing. 
            customRaisedMsg =
              string.Format("Event raised at: {0}",
              EventTime.ToString());

            // Raise the event.
            base.Raise();
        }


        // Raises the SampleWebBaseEvent.
        public void CustomRaise(
            System.Web.Management.WebBaseEvent evnt)
        {
            
            // Raise the event.
            Raise(evnt);
        }


        // Gets the event code.
        public int GetEventCode(bool detail)
        {
            int eCode;

            if (!detail)
                // Get the event code.
                eCode = EventCode;

            else
                // Get the detail event code.
                eCode = EventDetailCode;

            return eCode;
        }

        // Gets the event sequence.
        public long GetEventSequence()
        {
            // Get the event sequence.
            long eventSequence = EventSequence;
            return eventSequence;
        }

        // Gets the event source.
        public Object GetEventSource()
        {
            // Get the event source.
            Object source = this.EventSource;
            return source;
        }

        // Gets the event time.
        public DateTime GetEventTime()
        {
            // Get the event source.
            DateTime eTime = EventTime;
            return eTime;
        }

        // Gets the event time.
        public DateTime GetEventTimeUtc()
        {
            // Get the event source.
            DateTime eTime = EventTimeUtc;
            return eTime;
        }

        // Gets the event sequence.
        public string GetEventMessage()
        {
            // Get the event message.
            string eventMsg = Message;
            return eventMsg;
        }

        // Gets the current application information.
        public WebApplicationInformation GetEventAppInfo()
        {
            // Get the event message.
            WebApplicationInformation appImfo = 
                ApplicationInformation;
            return appImfo;
        }

        // Implements the ToString() method.
        public override string ToString()
        {
            return base.ToString();
        }

        // Implements the ToString(bool, bool) method.
        public string customToString(bool includeAppInfo, 
            bool includeCustomInfo)
        {
            return (
                base.ToString(includeAppInfo, 
                includeCustomInfo));
        }

        // Gets the event identifier.
        public Guid GetEventId()
        {
            Guid evId =  EventID;
            return evId;
        }

        //Formats Web request event information.
        public override void FormatCustomEventDetails(
            WebEventFormatter formatter)
        {
            base.FormatCustomEventDetails(formatter);

            // Add custom data.
            formatter.AppendLine("");

            formatter.IndentationLevel += 1;

            formatter.TabSize = 4;

            formatter.AppendLine(
                 "*SampleWebBaseEvent Start *");

            // Display custom event information.
            formatter.AppendLine(customCreatedMsg);
            formatter.AppendLine(customRaisedMsg);
            formatter.AppendLine(firingRecordInfo);

            formatter.AppendLine(
          "* SampleWebBaseEvent End *");


            formatter.IndentationLevel -= 1;
        }
    }
}

Imports System.Text
Imports System.Web
Imports System.Web.Management


Public Class SampleWebBaseEvent
    Inherits System.Web.Management.WebBaseEvent
    Implements System.Web.Management.IWebEventCustomEvaluator


    Private customCreatedMsg, customRaisedMsg As String

    ' Store firing record info.
    Private Shared firingRecordInfo As String

    ' Implements the IWebEventCustomEvaluator.CanFire 
    ' method. It is called by the ASP.NET if this custom
    ' type is configured in the profile
    ' element of the healthMonitoring section.
    Public Function CanFire( _
    ByVal e As System.Web.Management.WebBaseEvent, _
    ByVal rule As RuleFiringRecord) As Boolean _
    Implements System.Web.Management.IWebEventCustomEvaluator.CanFire

        Dim fireEvent As Boolean
        Dim lastFired As String = _
            rule.LastFired.ToString()
        Dim timesRaised As String = _
            rule.TimesRaised.ToString()

        ' Fire every other event raised.
        fireEvent = _
        IIf(rule.TimesRaised Mod 2 = 0, True, False)

        If fireEvent Then
            firingRecordInfo = String.Format( _
            "Event last fired: {0}", lastFired) + _
            String.Format( _
            ". Times raised: {0}",  timesRaised) 
          
        Else
            firingRecordInfo = String.Format( _
            "Event not fired. Times raised: {0}", _
            timesRaised)
        End If

        Return fireEvent

    End Function 'CanFire

 
    ' Invoked in case of events identified only by 
    ' their event code.
    Public Sub New(ByVal msg As String, _
    ByVal eventSource As Object, _
    ByVal eventCode As Integer)
        MyBase.New(msg, eventSource, eventCode)
        ' Perform custom initialization.
        customCreatedMsg = String.Format( _
        "Event created at: {0}", DateTime.Now.TimeOfDay.ToString())

    End Sub


    ' Invoked in case of events identified by their 
    ' event code.and related event detailed code.
    Public Sub New(ByVal msg As String, _
    ByVal eventSource As Object, _
    ByVal eventCode As Integer, _
    ByVal eventDetailCode As Integer)
        MyBase.New(msg, eventSource, _
        eventCode, eventDetailCode)
        ' Perform custom initialization.
        customCreatedMsg = String.Format( _
        "Event created at: {0}", DateTime.Now.TimeOfDay.ToString())

    End Sub


    ' Raises the SampleWebBaseEvent.
    Public Overrides Sub Raise()
        ' Perform custom processing. 
        customRaisedMsg = String.Format( _
        "Event raised at: {0}", DateTime.Now.TimeOfDay.ToString())

        ' Raise the event.
        MyBase.Raise()

    End Sub

    ' Raises the SampleWebBaseEvent.
    Public Sub CustomRaise(ByVal evnt _
    As System.Web.Management.WebBaseEvent)

        ' Raise the event.
        Raise(evnt)

    End Sub


    ' Gets the event code.
    Public Function GetEventCode(ByVal detail _
    As Boolean) As Integer
        Dim eCode As Integer

        If Not detail Then
            ' Get the event code.
            eCode = EventCode
            ' Get the detail event code.
        Else
            eCode = EventDetailCode
        End If
        Return eCode

    End Function 'GetEventCode


    ' Gets the event sequence.
    Public Function GetEventSequence() As Long
        ' Get the event sequence.
        Dim eventSequence As Long = eventSequence
        Return eventSequence

    End Function 'GetEventSequence



    ' Gets the event source.
    Public Function GetEventSource() As [Object]
        ' Get the event source.
        Dim [source] As [Object] = Me.EventSource
        Return [source]

    End Function 'GetEventSource

    ' Gets the event time.
    Public Function GetEventTime() As DateTime
        ' Get the event source.
        Dim eTime As DateTime = EventTime
        Return eTime

    End Function 'GetEventTime

    ' Gets the event time.
    Public Function GetEventTimeUtc() As DateTime
        ' Get the event source.
        Dim eTime As DateTime = EventTimeUtc
        Return eTime

    End Function 'GetEventTimeUtc

    ' Gets the event sequence.
    Public Function GetEventMessage() As String
        ' Get the event message.
        Dim eventMsg As String = Message
        Return eventMsg

    End Function 'GetEventMessage

    ' Gets the current application information.
    Public Function GetEventAppInfo() As WebApplicationInformation
        ' Get the event message.
        Dim appImfo As WebApplicationInformation = _
        ApplicationInformation
        Return appImfo

    End Function 'GetEventAppInfo

    ' Implements the ToString() method.
    Public Overrides Function ToString() As String
        Return MyBase.ToString()

    End Function 'ToString

    ' Implements the ToString(bool, bool) method.
    Public Function customToString(ByVal includeAppInfo As Boolean, _
    ByVal includeCustomInfo As Boolean) As String
        Return MyBase.ToString(includeAppInfo, includeCustomInfo)

    End Function 'customToString

    ' Gets the event identifier.
    Public Function GetEventId() As Guid
        Dim evId As Guid = EventID
        Return evId

    End Function 'GetEventId

    
    'Formats Web request event information.
    Public Overrides Sub FormatCustomEventDetails( _
ByVal formatter As WebEventFormatter)
        MyBase.FormatCustomEventDetails(formatter)

        ' Add custom data.
        formatter.AppendLine("")

        formatter.IndentationLevel += 1
        
        formatter.TabSize = 4
        
        formatter.AppendLine("*SampleWebBaseEvent Start *")
        formatter.AppendLine("Custom information goes here")
        formatter.AppendLine("* SampleWebBaseEvent End *")
        ' Display custom event timing.
        formatter.AppendLine(customCreatedMsg)
        formatter.AppendLine(customRaisedMsg)
        formatter.IndentationLevel -= 1

    End Sub

End Class

The following is an excerpt of the configuration file that enables ASP.NET to use the CanFire method to decide whether the raised event must be sent to the provider for processing.

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

    <providers>  
      <add name="SampleWebEventProvider"   
        type="SamplesAspNet.SampleEventProvider, webeventprovider, Version=1.0.1741.20369, Culture=neutral, PublicKeyToken=cf85aa6c978d9dea, processorArchitecture=MSIL" />  
    </providers>  

    <profiles>  
      <add   
        name="Custom"   
        minInstances="1"   
        maxLimit="Infinite"   
        minInterval="00:00:00"   
        custom ="SamplesAspNet.SampleWebRequestEvent,webrequestevent"   
        />  
    </profiles>  

    <eventMappings>  

      <add name="SampleWebRequestEvent" type="SamplesAspNet.SampleWebRequestEvent,webrequestevent, Version=1.0.1759.20533, Culture=neutral, PublicKeyToken=0d72899b07049076, processorArchitecture=MSIL" />  

    </eventMappings>  

    <rules>  
      <clear />  

        <add name="Custom Web Request Event"   
          eventName="SampleWebRequestEvent"  
          provider="SampleWebEventProvider" 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.

This interface allows enabling or disabling the firing of a specific event. This is especially useful when you implement your own custom event and want to control the rate at which it is sent to the related provider for processing.

Note

This interface does not control how often the event is raised. It only controls how often the event information is sent to the provider for processing.

Methods

CanFire(WebBaseEvent, RuleFiringRecord)

Evaluates whether an event should be raised.

See also

• RuleFiringRecord
• ASP.NET Health Monitoring Overview