Eric lippert - Amazon Web Services

azure mobile services
Push Notifications in
Windows 8 Apps
Sumit Maitra introduces the Windows Push Notification Service and how to
implement it for Windows 8 Store Apps using Azure Mobile Services
With the popularity of Smart Phones and
always connected (to internet) devices,
‘push notifications’ have gained immense
popularity. Though push notifications are
not new and Exchange had implemented
Active Sync quite some time back,
smartphones have made them
ubiquitous and brought them out of the
Enterprise-y setups. So today, we often
receive updates instead of looking
(polling) for updates. This can be a more
efficient process depending on the
implementation.
Common examples of Push
notification usage are, mail clients that
receive new mail notifications as they
come to their server’s Inbox. E.g. Social
Media apps that push updates to all
subscribed as soon as someone makes
an update to their status or games that
can push leaderboard updates of your
position changes and so on.
Given the popularity and utility of Push
Notifications, it’s a desired feature to
have in mobile applications. However,
setting up the infrastructure to do so
is non-trivial on any client (Windows
Phone, iOS, Android or Windows 8)
platform. This is where the Windows
Azure Team has stepped in with the
Windows Azure Mobile Services that
among other things, aim to ease the
burden of building Push Notification
infrastructure for connected apps.
Today, we will see how to build a
Windows 8 Store App that is capable
of receiving push notifications. For the
backend infrastructure we will use
Windows Azure Mobile Services.
Windows (Push)
Notification Service
The underlying infrastructure that enables Push notifications is
referred to as Windows Push Notification Service or WNS for short.
The typical process is as follows:
1. You first get an App SID and Client Secret for your Windows 8
Store App and store it in your Web Service.
2. Next your App requests Windows for a ‘Channel’ and sends it to
your WebService so that it can track the channels.
3. When one of the clients submit some data to your web service
that needs to send out push notifications, the web service provides
WNS with the SID and Client secret along with the channel details for
the notification to propagate.
Figure: Relationship between the various components that your app must communicate with, for WNS to work
4. All clients that the data was intended for, then receive the push notification. The clients could be direct recipients or subscribed for by the client
5. Notifications in Windows 8 can be
a. Tile notifications (primary/secondary)
b. Toast notifications (for toast popup)
c. Raw notifications (to download data)
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