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Debugging Tips
When using push notifications, experience shows that if notifications aren’t getting through, it’s typically
not a problem with WNS. Here’s a list of things to check (thanks to Hans Andersen for this list):
• Check the return status of your HTTP POSTs to WNS. If it’s returning an HTTP 200 response,
check the X-WNS-NotificationStatus and other headers you get back. Look particularly for the
status of “Received,” which indicates that a notification has gone to the client.
• Lacking anything conclusive in the headers, run Event Viewer and check the events under
Application And Services Logs > Microsoft > Windows > Push Notifications Platform >
Operational to see the activity.
• Also look under Application And Services Logs > Microsoft > Windows > Immersive-Shell >
Microsoft-Windows-TWinUI > Operational to see if there are error messages related to XML
parsing about the same time you expected to receive a notification.
• Even if the XML is well-formed, an update might not show up if a referenced image is either too
large (pixel dimensions or file size), if the image is the wrong format (for example, TIF), if the
image is corrupt, if the server handling the image request can’t handle the query parameters for
the tile (scaling, contrast, language), or if the server is encountering other errors as might be
revealed in its own logs.
• If updates appear but after a considerable delay, it could just mean internal timeouts or other
network latency within the tile and notification infrastructure. If this happens, just accept that the
world isn’t always perfect and operations must sometimes be retried!
Windows Azure Toolkit and Windows Azure Mobile Services
Clearly, plenty of work is involved to create a service capable of receiving channel URIs and sending
notifications through WNS. Recognizing this, the Windows Azure Toolkit once again provides some
solutions. Going into all the details is beyond the scope of this book, but the link above will get you
started. More specifically, check out the Azure Notifications Samples and the Raw Notifications Sample,
as well as the Push Notification Worker sample. There is also a helpful video on the Channel 9 site:
Episode 73 – Nick Harris on Push Notifications for Windows 8. Additional resources have likely been
published since this chapter was written, so a quick Internet search will likely turn up more.
Also check out Windows Azure Mobile Services, which helps you create a scalable backend for an
app, including structured cloud data, authentication, and push notifications. This is quite new as of the
time of writing, so I don’t have links to other resources, but it’s certainly worth looking into.
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