Azure Notification Hubs - Should I save the device token in my server?

Question

I am using Azure Notification Hubs to deliver push notifications to an android/iPhone devices.

My general flow is:

1.Every time the user opens the mobile app, a call is made to the PNS (APNS/GCM) and gets an updated device token.
2. The device token is then sent to the server.
3. The server executes the following code to register the token:

RegistrationDescription reg;

if (deviceType == DeviceType.Iphone)
{
    reg = new AppleRegistrationDescription(deviceToken, new string[] { userId.ToString() });
}
else
{
    reg = new GcmRegistrationDescription(deviceToken, new string[] { userId.ToString() });
}

reg = await hub.CreateRegistrationAsync(reg);

It works great, but my question is, should I be tracking those device tokens in my server for some reason? For example save them in a table for later use or other scenarios I could be facing, or it's intended to use that way(without saving them in a table).

efimovandr efimovandr · Accepted Answer · 2015-04-20T23:07:30

Your code creates a lot of duplicates, by duplicate I mean different registrations with same PNS handle (APNS device token or GCM registration id). NH has de-duplication logic which prevents your devices from receiving multiple copies of same message, but it increases internal storage space and slows system down.

So there is recommendation:

On each device your create and store some GUID-like identifier;
You pass that identifier on server together with PNS handle;
On server you do hub.GetRegistrationByTagAsync(deviceGuid, 100);
If registration returned, then update it with received PNS handle (even if PNS handle the same - just to prevent expiration);
If result is empty, then you create new registration specifying device GUID as a tag;

Also there is new API which allows you to do only one call and not use any tags if you don't need them. https://msdn.microsoft.com/en-us/magazine/dn948105.aspx Look at topic Case 2: The Back End Manages Devices in Notification Hubs. It is not very good explanation maybe but feature is new. If any questions about that API then I can answer.

Azure Notification Hubs - Should I save the device token in my server?

1 Answers