سؤال عن كيفية نعمل Real-time notification مثل ال فيس بوك باسفل الصفحة

<asp:ScriptManager ID="ScriptManager1" runat="server">

</asp:ScriptManager>

<asp:TextBox ID="TextBox1" runat="server" Height="155px" TextMode="MultiLine"

Width="359px"></asp:TextBox>

<asp:UpdatePanel ID="UpdatePanel1" runat="server">

<Triggers>

<asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick" />

</Triggers>

<ContentTemplate>

<div style="background-color:Gray"><b>Notification</b><br />

<asp:Label ID="lblVisitors" runat="server" Text="Visitors: 0"></asp:Label>

</div>

</ContentTemplate>

</asp:UpdatePanel>

<asp:Timer ID="Timer1" runat="server" Enabled="true" Interval="3000">

</asp:Timer>

Public Class _Default

Inherits System.Web.UI.Page

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

If Application("visitors") Is Nothing Then Application("visitors") = 0

End Sub

Protected Sub Timer1_Tick(ByVal sender As Object, ByVal e As EventArgs) Handles Timer1.Tick

lblVisitors.Text = "Visitors: " & Application("visitors")

Application("visitors") = Convert.ToInt32(Application("visitors")) + 1

End Sub

End Class