EventClassCallback callback function

[Do not implement this function; it may be unavailable in subsequent versions.]

Consumers implement this function to receive events for a specific event trace class from a session. ETW calls this function every time the ProcessTrace function process an event belonging to the event trace class.

The PEVENT_CALLBACK type defines a pointer to this callback function. EventClassCallback is a placeholder for the application-defined function name.


VOID WINAPI EventClassCallback(
  _In_ PEVENT_TRACE pEvent


pEvent [in]

Pointer to an EVENT_TRACE structure that contains the event information.

Return value

The function does not return a value.


To associate each EventClassCallback function with the class GUID of the event trace class it processes, use the SetTraceCallback function.

To stop the EventClassCallback from receiving events, call the RemoveTraceCallback function.

To processes all events that the session generates, see the EventCallback function.

If you use both EventCallback and EventClassCallback to receive events, the event is always sent to EventCallback and is only sent to EventClassCallback if the event matches the class GUID associated with the callback.

You use the Header.Class.Type member of EVENT_TRACE to determine the type of event you received. If you are consuming events from your own provider and know the layout of the data, this is not an issue. Otherwise, to interpret the event, the provider must have published their event schema in the \\root\wmi namespace. For information on using an event's MOF schema to interpret the event, see Consuming Events.


Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]



See also