Spooler notification terminology

The following terms are used in the discussion of asynchronous spooler notification:

Term	Description
callback interface	When a listening client registers for notifications, it must provide a pointer to an IPrintAsyncNotifyCallback interface. The methods of this interface are called back when notifications arrive or when the channel is closed.
listening clients	Either applications or spooler internal components registered to receive print notifications. This is different from what was previously referred to as the clients of the spooler notification pipe. A client of the spooler notification pipe is whatever component defines a notification type and schema.
notification	Data sent through the notification channel between the printing components and listening clients.
notification channel	A logical component. It is represented by an IPrintAsyncNotifyCallback interface pointer. The printing component creates the notification channel when it needs to send out notifications. The listening client uses the notification channel when it sends data back to the printing component.
notification registration handle	The handle created by the service when a listening clients registers for receiving notifications. The listening client can use this handle to unregister for notifications.
printing component	Components loaded by Spoolsv.exe, such as print processors, drivers, and monitors.
service	Functionality implemented by the spooler, either as part of the service itself (Spoolsv.exe) or as part of the client side (Winspool.drv).