A scheduled task allows you to perform an activity in the background while your app is or is not running. A task can be used to query a cloud service and update the app’s shell tiles, and it provides your users with the opportunity to respond to some event.
Scheduled tasks follow the same model as scheduled notifications, yet they add one other dimension: user-defined task agents. Whereas scheduled notifications rely solely on built-in task agents for presenting notification dialogs, with scheduled tasks, you define your own.
Like scheduled notifications, scheduled tasks are registered with the
ScheduledActionService when your app is running. Registration causes your task agent to run in the background at an indeterminate time ...