Types of Events

Will Events

Event handlers called before the operation starts offer you the opportunity to examine or modify the operation parameters, then either cancel the operation or allow it to complete. These event handler routines usually have names of the form WillEvent (Will events).

Complete Events

Event handlers called after an operation completes can notify your application that an operation has concluded. Such an event handler is also notified when a pending operation is canceled by a Will event handler. These event handler routines usually have names of the form EventComplete (Complete events).

Will and Complete events are typically used in pairs.

The Other Events

The other event handlers—that is, events whose names are not of the form WillEvent or EventComplete—are called only after an operation completes.