Silverlight 4 with (HTTP) Duplex and SQL Notifications

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.IO;
using System.Linq;
using System.Net;
using System.Runtime.Serialization.Json;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.Xml;
using SLDuplexDependency.BrowserMaintenanceService;


namespace SLDuplexDependency
{
    public partial class MainPage : UserControl
    {
        DBNotificationClient client;   

        public MainPage()
        {
            InitializeComponent();
            this.InitialisePageFunctionality();         
        }

        /// <summary>
        /// Initialises the page functionality.
        /// </summary>
        void InitialisePageFunctionality()
        {         
            // make initial call to get employees and bind Sqldependency object to database
            SqlServiceReference.SqlNotificationsClient dbService = new SqlServiceReference.SqlNotificationsClient();
            dbService.GetEmployeeListCompleted += new EventHandler<SqlServiceReference.GetEmployeeListCompletedEventArgs>(InitialGetEmployeesCompleted); // method to call after initial data retrival
            dbService.GetEmployeeListAsync(DateTime.Now.AddYears(-50), DateTime.Now.AddYears(10));

            // reference the notifications service and craete the callback hook for database changes
            client = new DBNotificationClient(new PollingDuplexHttpBinding(), new EndpointAddress("http://localhost:52333/DBNotificationService/DBNotificationService.svc"));
            client.SendNotificationToClientsReceived += (sender, e) =>
            {
                if (e.data != null) UpdatedAuthorsReceived(e.data); // something to process
            };

            this.Subscribe(); // make the browser (instance) known to server
        }

        /// <summary>
        /// Initial method for binding the data to the grid
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The <see cref="SLDuplexDependency.SqlServiceReference.GetEmployeeListCompletedEventArgs"/> instance containing the event data.</param>
        void InitialGetEmployeesCompleted(object sender, SLDuplexDependency.SqlServiceReference.GetEmployeeListCompletedEventArgs e)
        {
            this.authorGrid.ItemsSource = e.Result;
        }

        /// <summary>
        /// Update the grid with new, updated or deleted employee data.
        /// </summary>
        /// <param name="data">The data.</param>
        void UpdatedAuthorsReceived(string data)
        {            
            this.authorGrid.ItemsSource = DeserializeObject(data);
        }

        /// <summary>
        /// Subscribes this instance of the browser,
        /// </summary>
        void Subscribe()
        {            
            client.SubscribeToNotificationsCompleted += (sender, e) => { };
            client.SubscribeToNotificationsAsync();
        }

        /// <summary>
        /// Unsubscribes this instance of the browser
        /// </summary>
        void Unsubscribe()
        {            
            client.UnsubscribeToNotificationsCompleted += (sender, e) => { };
            client.UnsubscribeToNotificationsAsync();
        }

        /// <summary>
        /// Deserializes the object.
        /// </summary>
        /// <param name="pObject">The p object.</param>
        /// <returns></returns>
        List<SqlServiceReference.Employee> DeserializeObject(Object objEmployees)
        {
            try
            {
                MemoryStream mryStmObj = new MemoryStream(Encoding.UTF8.GetBytes(objEmployees.ToString()));
                DataContractJsonSerializer serialiser = new DataContractJsonSerializer(typeof(List<SLDuplexDependency.SqlServiceReference.Employee>));
                return (List<SqlServiceReference.Employee>)serialiser.ReadObject(mryStmObj);                
            }
            catch (Exception) {return null;}
        }
    }
}