EventAttribute Class


Specifies additional event schema information for an event.

public ref class EventAttribute sealed : Attribute
public sealed class EventAttribute : Attribute
type EventAttribute = class
    inherit Attribute
Public NotInheritable Class EventAttribute
Inherits Attribute


The following example shows how to use the EventAttribute class to define a variety of events. This code example is part of a larger example provided for the EventSource class.

[Event(1, Message = "Application Failure: {0}", Level = EventLevel.Error, Keywords = Keywords.Diagnostic)]
public void Failure(string message) { WriteEvent(1, message); }
<[Event](1, Message:="Application Failure: {0}", Level:=EventLevel.Error, Keywords:=Keywords.Diagnostic)> _
Public Sub Failure(ByVal message As String)
    WriteEvent(1, message)
End Sub
[Event(2, Message = "Starting up.", Keywords = Keywords.Perf, Level = EventLevel.Informational)]
public void Startup() { WriteEvent(2); }
<[Event](2, Message:="Starting up.", Keywords:=Keywords.Perf, Level:=EventLevel.Informational)> _
Public Sub Startup()
End Sub
[Event(3, Message = "loading page {1} activityID={0}", Opcode = EventOpcode.Start,
    Task = Tasks.Page, Keywords = Keywords.Page, Level = EventLevel.Informational)]
public void PageStart(int ID, string url) { if (IsEnabled()) WriteEvent(3, ID, url); }
<[Event](3, Message:="loading page {1} activityID={0}", Opcode:=EventOpcode.Start, Task:=Tasks.Page, Keywords:=Keywords.Page, Level:=EventLevel.Informational)> _
Public Sub PageStart(ByVal ID As Integer, ByVal url As String)
    If IsEnabled() Then
        WriteEvent(3, ID, url)
    End If
End Sub
[Event(4, Opcode = EventOpcode.Stop, Task = Tasks.Page, Keywords = Keywords.Page, Level = EventLevel.Informational)]
public void PageStop(int ID) { if (IsEnabled()) WriteEvent(4, ID); }
<[Event](4, Opcode:=EventOpcode.Stop, Task:=Tasks.Page, Keywords:=Keywords.Page, Level:=EventLevel.Informational)> _
Public Sub PageStop(ByVal ID As Integer)
    If IsEnabled() Then
        WriteEvent(4, ID)
    End If
End Sub


When you apply this attribute to an ETW event method defined on an EventSource-derived class, you must call the WriteEvent method on the base class, passing the event ID, followed by the same arguments as the defined method is passed. You should follow the pattern shown in the following examples.



Initializes a new instance of the EventAttribute class with the specified event identifier.



Specifies the behavior of the start and stop events of an activity. An activity is the region of time in an app between the start and the stop.


Gets or sets an additional event log where the event should be written.


Gets or sets the identifier for the event.


Gets or sets the keywords for the event.


Gets or sets the level for the event.


Gets or sets the message for the event.


Gets or sets the operation code for the event.


Gets or sets the EventTags value for this EventAttribute object. An event tag is a user-defined value that is passed through when the event is logged.


Gets or sets the task for the event.


When implemented in a derived class, gets a unique identifier for this Attribute.

(Inherited from Attribute)

Gets or sets the version of the event.



Returns a value that indicates whether this instance is equal to a specified object.

(Inherited from Attribute)

Returns the hash code for this instance.

(Inherited from Attribute)

Gets the Type of the current instance.

(Inherited from Object)

When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.

(Inherited from Attribute)

When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.

(Inherited from Attribute)

Creates a shallow copy of the current Object.

(Inherited from Object)

Returns a string that represents the current object.

(Inherited from Object)

Explicit Interface Implementations

_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.

(Inherited from Attribute)
_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can be used to get the type information for an interface.

(Inherited from Attribute)

Retrieves the number of type information interfaces that an object provides (either 0 or 1).

(Inherited from Attribute)
_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.

(Inherited from Attribute)

Applies to