Here is an example screenshot and all the code\markup required… I’d love to hear what you think… do you think this makes for a compelling demo?

Html for search box and “submit” link (default.aspx)

<div id="links">
   Search for
   <asp :TextBox ID="searchtext" runat="server" CssClass="searchbox" ></asp> 
   <asp :LinkButton ID="LinkButton1" runat="server" OnClick="LinkButton1_Click">go</asp><br />
</div>

ASP.NET handler for the LinkButton (default.aspx)

protected void LinkButton1_Click(object sender, EventArgs e)
{
   StringCollection list = Profile.SearchTerms;
   if (!list.Contains(searchtext.Text))
   {
      list.Add(searchtext.Text);
   }
   //TODO: Do search
}

ASP.NET AJAX goodness (default.aspx)

<asp :ScriptManager ID="ScriptManager" runat="server" />
<asp :AutoCompleteExtender ID="AutoCompleteExtender1" TargetControlID="searchtext"
                          runat="server" ServiceMethod="GetCompletionList"
                          ServicePath="~/SearchAutoComplete.asmx" MinimumPrefixLength="1" />

Web Service Implementation (SearchAutoComplete.asmx)

[WebMethod]
public string[] GetCompletionList(string prefixText, int count)
{
   StringCollection list = (StringCollection)HttpContext.Current.Profile["SearchTerms"];
   List<string> suggestions = new List</string><string>();
   foreach (string s in list)
   {
      if (s.StartsWith(prefixText))
      {
         suggestions.Add(s);
      }
   }
   return suggestions.ToArray();
}
</string>

Profile Config Section – (Web.config in )

<profile>
   <properties>
      <add name="SearchTerms"
           type="System.Collections.Specialized.StringCollection"
           serializeAs="Xml" />
    </properties>
</profile>

Exercises left for the user

* Clean up any bad or misleading search terms
* Sort hits by relevance
* Add a hit count
* Age out older results
Demo: http://www.google.com
Source: http://blogs.msdn.com/brada/archive/2006/10/27/search-autocomplete-with-asp-net-ajax-extensions.aspx

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