Update Panel and AJAX Timer - Removing all controls on each Tick event
<p>I have an ASP.NET UpdatePanel Triggered to refresh based on the Tick event of a Timer.</p>

<p>The page parses a custom XML file and inserts UserControls (containing GridViews) on the fly.  This is executed from the <code>Page_Load</code> method.</p>

<pre><code>if(!Page.IsPostBack)
  parseXmlFile();
</code></pre>

<p>The first time the page loads, all the controls are displayed as expected.  The problem is that the first time the timer <code>Tick</code> event is fired, all the UserControls disappear.</p>

<p>In the <code>Tick</code> event I call a custom method <code>RefreshData()</code> which in turn rebinds the data to the GridView via an SqlDataSource.</p>

<pre><code>   public void RefreshData() {
       GridView1.DataBind();
   ...
</code></pre>

<p>Maybe I don't understand how AJAX works in ASP.NET. </p>

<p>I only want to parse the XML file once (which creates all the UserControls in the page).  From this point I just want to refresh the data contained in the GridView and change the Visibility state of the GridView.</p>
