title: how can recognize Timer's callback (Timer Is In Master Page) In both Master & Content Page
body: <p>my pages are base on master and content pages in asp.net with c#.<br>
  i have a timer in master page like below :  </p>
  
  <pre><code>                    &lt;asp:UpdatePanel ID="UpdatePanel1" runat="server"&gt;
                          &lt;ContentTemplate&gt;
                              &lt;asp:Timer runat="server" ID="Timer1" Interval="10000" Enabled="False"&gt;
                              &lt;/asp:Timer&gt;
                              &lt;div id="SiteStatistics"&gt;
                                  &lt;asp:Label ID="lblDownload_Count_Title" runat="server" Text="Download Count :" ToolTip="Download Count :"
                                      CssClass="lblTitleInStatistics"&gt;&lt;/asp:Label&gt;
                                  &lt;asp:Label ID="lblDownload_Count" runat="server" Text="&lt;%# Download_Count() %&gt;" CssClass="lblCountInStatistics"&gt;&lt;/asp:Label&gt;
                                  &lt;br /&gt;
                                  &lt;asp:Label ID="lblDownload_Count_By_UserID_Title" runat="server" Text="Ur Download Count :"
                                      ToolTip="Your Download Count From The Begining Of Registration UpTo Now" CssClass="lblTitleInStatistics"&gt;&lt;/asp:Label&gt;
                                  &lt;asp:Label ID="lblDownload_Count_By_UserID" runat="server" Text="&lt;%# Download_Count_By_UserID() %&gt;"
                                      CssClass="lblCountInStatistics"&gt;&lt;/asp:Label&gt;
                                  &lt;br /&gt;
                                  &lt;asp:Label ID="lblDownload_Count_By_UserID_Today_Title" runat="server" Text="Ur Download Count-Today :"
                                      ToolTip="Your Download Count-Today" CssClass="lblTitleInStatistics"&gt;&lt;/asp:Label&gt;
                                  &lt;asp:Label ID="lblDownload_Count_By_UserID_Today" runat="server" Text="&lt;%# Download_Count_By_UserID_Today() %&gt;"
                                      CssClass="lblCountInStatistics"&gt;&lt;/asp:Label&gt;
                                  &lt;br /&gt;
                                  &lt;asp:Label ID="lblDownload_Size_By_UserID_Title" runat="server" Text="Ur Download Size :"
                                      ToolTip="Your Download Size From The Begining Of Registration UpTo Now" CssClass="lblTitleInStatistics"&gt;&lt;/asp:Label&gt;
                                  &lt;asp:Label ID="lblDownload_Size_By_UserID" runat="server" Text="&lt;%# Download_Size_By_UserID() %&gt;"
                                      CssClass="lblCountInStatistics"&gt;&lt;/asp:Label&gt;
                                  &lt;br /&gt;
                                  &lt;asp:Label ID="lblDownload_Size_By_UserID_Today_Title" runat="server" Text="Ur Download Size-Today :"
                                      ToolTip="Your Download Size-Today" CssClass="lblTitleInStatistics"&gt;&lt;/asp:Label&gt;
                                  &lt;asp:Label ID="lblDownload_Size_By_UserID_Today" runat="server" Text="&lt;%# Download_Size_By_UserID_Today() %&gt;"
                                      CssClass="lblCountInStatistics"&gt;&lt;/asp:Label&gt;
                                  &lt;br /&gt;
                                  &lt;asp:Label ID="lblDownload_Size_By_UserID_Today_Remain_Title" runat="server" Text="Ur Remain Download Size-Today :"
                                      ToolTip="Your Remain Download Size-Today" CssClass="lblTitleInStatistics"&gt;&lt;/asp:Label&gt;
                                  &lt;asp:Label ID="lblDownload_Size_By_UserID_Today_Remain" runat="server" Text="&lt;%# Download_Size_By_UserID_Today_Remain() %&gt;"
                                      CssClass="lblCountInStatistics"&gt;&lt;/asp:Label&gt;
                              &lt;/div&gt;
                          &lt;/ContentTemplate&gt;
                      &lt;/asp:UpdatePanel&gt;
  </code></pre>
  
  <p>this timer ticks every 10 seconds and causes callbacks -> first page_load of content page and last page_load of master page fire every 10 seconds because of that timer!<br>
  how can i recognize that <strong>timer'callback</strong> in both master and content pages and prevent running codes again and again because of callback?   </p>
  
  <p>thanks in advance</p>