Csharp classes demonstrating how to send push notifications to a specific registration using tag expressions in Azure Mobile Apps

NotificationController.cs

using System.Linq;
using System.Threading.Tasks;
using System.Web.Http;
using System.Web.Http.Controllers;
using System.Web.Http.OData;
using System.Web.Http.Tracing;
using Microsoft.Azure.Mobile.Server;
using App.Models;
using App.Notification;

namespace Controllers
{
    public class NotificationController : TableController<Notification>
    {
        private ITraceWriter traceWriter;

        private NotificationSender notificationSender;

        protected override void Initialize(HttpControllerContext controllerContext)
        {
            base.Initialize(controllerContext);
            AppContext context = new AppContext();
            DomainManager = new EntityDomainManager<Notification>(context, Request);
            traceWriter = Configuration.Services.GetTraceWriter();
            notificationSender = new NotificationSender(Configuration);
        }

        public IQueryable<Notification> GetAllNotifications()
        {
            return Query(); 
        }

        public SingleResult<Notification> GetNotification(string id)
        {
            return Lookup(id);
        }

        public Task<Notification> PatchNotification(string id, Delta<Notification> patch)
        {
             return UpdateAsync(id, patch);
        }

        public async Task<IHttpActionResult> PostNotification(Notification item)
        {
            Notification current = await InsertAsync(item);

            await notificationSender.SendPush("Você tem uma nova notificaçao", item.Mensagem, current.personId);

            return CreatedAtRoute("Tables", new { id = current.Id }, current);
        }

        public Task DeleteNotification(string id)
        {
             return DeleteAsync(id);
        }
    }
}

NotificationSender.cs

using Microsoft.Azure.Mobile.Server;
using Microsoft.Azure.Mobile.Server.Config;
using Microsoft.Azure.NotificationHubs;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using System.Web.Http;
using System.Web.Http.Tracing;

namespace Notification
{
    public class NotificationSender
    {
        private NotificationHubClient hub;

        private ITraceWriter traceWriter;

        public NotificationSender(HttpConfiguration config)
        {
            MobileAppSettingsDictionary settings =
                config.GetMobileAppSettingsProvider().GetMobileAppSettings();

            // Get the Notification Hubs credentials for the Mobile App.
            string notificationHubName = settings.NotificationHubName;
            string notificationHubConnection = settings
                .Connections[MobileAppSettingsKeys.NotificationHubConnectionString].ConnectionString;

            // Create a new Notification Hub client.
            hub = NotificationHubClient
                .CreateClientFromConnectionString(notificationHubConnection, notificationHubName);

            traceWriter = config.Services.GetTraceWriter();
        }

        public async Task SendPush(string title, string message, string tagExpression = null)
        {
            // Sending the message so that all template registrations that contain "messageParam"
            // will receive the notifications. This includes APNS, GCM, WNS, and MPNS template registrations.
            Dictionary<string, string> templateParams = new Dictionary<string, string>();
            templateParams["titleParam"] = title;
            templateParams["messageParam"] = message;

            try
            {
                // Send the push notification and log the results.
                NotificationOutcome result;
                if (tagExpression == null)
                {
                    result = await hub.SendTemplateNotificationAsync(templateParams);
                }
                else
                {
                    result = await hub.SendTemplateNotificationAsync(templateParams, tagExpression);
                }

                // Write the success result to the logs.
                traceWriter.Info(result.State.ToString());
            }
            catch (Exception ex)
            {
                // Write the failure result to the logs.
                traceWriter.Error(ex.Message, null, "Push.SendAsync Error");
            }
        }
    }
}