Update Parent UpdatePanel from Child UpdatePanel - Conditionally

Question

I am trying to trying to setup an updatepanel to update every X seconds, the problem is I don't want the control to actually refresh unless there is new data. So I currently have a child updatepanel in a parent UpdatePanel, the child updatepanel gets refreshed by a timer. But I can't seem to find a way to trigger the parent panel to update. Again, only when certain conditions(data changed) are met.

Sample Code:

<asp:Timer ID="Timer1" OnTick="Timer1_Tick" runat="server" Interval="10000"></asp:Timer>
<asp:updatepanel id="upParent" runat="server" UpdateMode="Conditional">
    <ContentTemplate>    
        <asp:Label id="lblParenttime" Runat="server">Parent Time Here</asp:Label>     
        <asp:updatepanel id="upChild" runat="server" UpdateMode="Conditional">
            <ContentTemplate>
                <asp:Label id="lblChildtime" Runat="server">Child Time Here</asp:Label>
            </ContentTemplate>
            <triggers>
                <asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick" />
            </triggers> 
        </asp:updatepanel>  
    </ContentTemplate>
</asp:updatepanel>  

Protected Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick
   lblChildtime.Text = Now.Tostring
   if X = Y then
       'Cause Parent to Update
       lblParenttime.Text = Now.Tostring
   end if     
End Sub

Answer 1

You can trigger some javascript when you UpdatePanel refreshes with the following javascript code:

var prm = Sys.WebForms.PageRequestManager.getInstance();
prm.add_pageLoaded(YourJavascriptFunctionNameHere);

You could then put a hidden button on the other UpdatePanel and manually call the __DoPostBack from the javascript function you have hooked onto the UpdatePanel reload.

There is probably other ideas for how to leverage add_pageLoaded in your scenario but this should at least get you on the right track.