Creating the Event Classes
Once the program object has received the IDebugEventCallback2 interface, you can use it to send events back to the session debug manager (SDM). All events are sent to the SDM as instances of classes derived from the IDebugEvent2 interface. The SDM determines the event type by examining the event identifier passed to IDebugEventCallback2::Event. The SDM will then obtain the appropriate interface from the event and call the methods of that interface for information particular to that event.
Sending the startup events tells the SDM that the program is ready to be debugged.