.Net Mobile Service Back-End for Notification Hub - azure

Question

I am currently writing a mobile application with Xamarin for Android and will be adding iOS once my company purchases a Mac so that I can start developing the iOS portion. I am currently trying to write a .Net Mobile Services back-end for Azure Notification Hub that will allow me to register the devices from the back end as well as send push notification to a specific user, and/or all users.
I have followed the Azure documentation all the way through Getting Started With Notification Hub and have successfully performed a single platform push. Moving beyond this example however is where I get stuck. Every example beyond this point completely drops Android support and only focuses on Windows Phone and iOS. I have watched a few Channel 9 videos regarding this subject and again it's all Windows Phone, Windows 8, and iOS based.
Does anyone have an example of a .Net Mobile Service back-end for Azure Notification Hub that will register the device to the notification hub from the back-end? Thank you for your time.

Answer 1

I don't have sample code on GitHub yet, but here's a gist of how to get NotificationHub working on Android.
using Microsoft.ServiceBus.Notifications;
using Newtonsoft.Json;
public class AndroidNotificationHub
{
private readonly NotificationHubClient _hubClient;
public AndroidNotificationHub()
{
const string cn = "YourConnectionStringHere";
const string hubPath = "YourHubPathHere";
_hubClient = NotificationHubClient.CreateClientFromConnectionString(cn, hubPath);
}
public async Task<RegistrationDescription> Register(string platform, string installationId, string registrationId, string userName)
{
// Get registrations for the current installation ID.
var regsForInstId = await _hubClient.GetRegistrationsByTagAsync(installationId, 100);
var updated = false;
var firstRegistration = true;
RegistrationDescription registration = null;
// Check for existing registrations.
foreach (var registrationDescription in regsForInstId)
{
if (firstRegistration)
{
// Update the tags.
registrationDescription.Tags = new HashSet<string>() { installationId, userName };
// We need to handle each platform separately.
switch (platform)
{
case "android":
var gcmReg = registrationDescription as GcmRegistrationDescription;
gcmReg.GcmRegistrationId = registrationId;
registration = await _hubClient.UpdateRegistrationAsync(gcmReg);
break;
}
updated = true;
firstRegistration = false;
}
else
{
// We shouldn't have any extra registrations; delete if we do.
await _hubClient.DeleteRegistrationAsync(registrationDescription);
}
}
// Create a new registration.
if (!updated)
{
switch (platform)
{
case "android":
registration = await _hubClient.CreateGcmNativeRegistrationAsync(registrationId, new[] { installationId, userName });
break;
}
}
return registration;
}
// Basic implementation that sends a notification to Android clients
public async Task<bool> SendNotification(int id, string from, string text, string tag)
{
try
{
var payload = new
{
data = new
{
message = new
{
// these properties can be whatever you want
id,
from,
text,
when = DateTime.UtcNow.ToString("s") + "Z"
}
}
};
var json = JsonConvert.SerializeObject(payload);
await _hubClient.SendGcmNativeNotificationAsync(json, tag);
return true;
}
catch (ArgumentException ex)
{
// This is expected when an APNS registration doesn't exist.
return false;
}
}
public async Task<bool> ClearRegistrations(string userName)
{
// Get registrations for the current installation ID.
var regsForInstId = await _hubClient.GetRegistrationsByTagAsync(userName, 100);
// Check for existing registrations.
foreach (var registrationDescription in regsForInstId)
{
// We shouldn't have any extra registrations; delete if we do.
await _hubClient.DeleteRegistrationAsync(registrationDescription);
}
return true;
}
}
Your Android client will need to call your backend's registration API during startup. I have an MVC action for this.
[HttpPost]
public async Task<ActionResult> Register(string platform, string installationId, string registrationId, string userName)
{
try
{
var hub = new AndroidNotificationHub();
var registration = await hub.Register(platform, installationId, registrationId, userName);
return Json(registration);
}
catch (Exception ex)
{
return Content(ex.ToString());
}
}
Once the mobile client has registered, you can then start sending notifications from your backend, by calling the SendNotification method.
Hope this points you in the right direction.