MICROSOFT_PRESS_EBOOK_PROGRAMMING_WINDOWS_8_APPS_WITH_HTML_CSS_AND_JAVASCRIPT_PDF

• Periodic updates for tiles and badges means providing Windows the URIs of web services to call
at selected intervals between 30 minutes and 24 hours. Periodic updates are the easiest and
lower-cost means to update a tile from a running web service.
• Push notifications for tiles, badges, toast notifications, and raw notifications (whatever data an
app wants to manage) can be used for higher-frequency, user-specific updates. This involves
creating web services that communicate with WNS to issue those notifications to specific
channel URIs, a process that is much more involved and expensive than periodic updates.
• Background tasks are small pieces of code that an app configures to run when certain triggers
occur, such as changes in connectivity, timers, receipt of push notifications, and app updates.
Apps should never depend on background tasks, however, because they are always under the
user’s control.
• Background task triggers can be refined through specific conditions to avoid running tasks when
it’s not necessary (such as when there is no connectivity).
• Some triggers require that the app has also been added to the lock screen. Such apps must first
request access, which is subject to user consent, and the user must specifically add the app
through PC Settings. Given that privilege, apps can issue badge updates and tile text to the lock
screen.
• Through maintenance triggers, apps can also set up tasks to run periodically when a device is on
AC power.
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