<%@ Control Language="VB" ClassName="WebUserControl" %>
<%@ Implements Interface="System.Web.UI.ICallbackEventHandler" %>

<script language="javascript" type="text/javascript">
// <![CDATA[
function returnBoxValue(val) {    
    CallServer(val, "");    
}

function ReceiveServerData(rValue) {
        document.getElementById("info").innerText = rValue;
}

// ]]>
</script>

<script runat="server">
    Protected returnedString As String
    
    Public Function GetCallbackResult() As String Implements System.Web.UI.ICallbackEventHandler.GetCallbackResult
        Return returnedString
    End Function
    
    Public Sub RaiseCallbackEvent(ByVal eventArgument As String) Implements System.Web.UI.ICallbackEventHandler.RaiseCallbackEvent
        returnedString = "This string from server: " & eventArgument
    End Sub
    
    Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
                     
        Dim cs As ClientScriptManager = Page.ClientScript
        Dim cstext As String
        Dim csname As String
        
        csname = "CallServer"
        If (Not cs.IsClientScriptBlockRegistered(Me.GetType(), csname)) Then
            cstext = "function CallServer(arg, context) { " & cs.GetCallbackEventReference(Me, "arg", "ReceiveServerData", "context") & "} ;"
            cs.RegisterClientScriptBlock(Me.GetType(), csname, cstext, True)
        End If
                                      
    End Sub
    
</script>

<table border="0" cellpadding="0" cellspacing="0">
    <tr>
        <td>
            <input id="Text1" onkeyup="returnBoxValue(this.value);" type="text" /></td>
    </tr>
    <tr>
        <td>
            <label id="info">
            </label>
        </td>
    </tr>
</table>