function getZipData(val)
        {
 	        loadXMLDoc('http://localhost/MyApplication/AAP123.aspx?proc=GetCity&Zip =' + val);
        }
        
        function loadXMLDoc(url) {
            req = new ActiveXObject("Microsoft.XMLHTTP");
            if (req) {
             alert(url)                
             req.onreadystatechange = processReqChange;
             req.open("GET", url, true);
             req.send();
            }
            
        }
        
        function processReqChange() {
            if (req.readyState ==  4 ) {
           
                if (req.status ==  200 ) {
    
                    document.forms[ 0 ].output.value  = req.responseText 
                    response  = req.responseXML.documentElement;
                    //City = response.getElementsByTagName('City')[ 0 ].firstChild.data;
                    //State = response.getElementsByTagName('State')[ 0 ].firstChild.data;
                    //document.forms[ 0 ].txtCity.value = City
                    //document.forms[ 0 ].txtState.value = State
                } else {
                    alert("Please enter a valid Zip code:\n" +
                    req.statusText);
                }
            }
        }

Partial Class AAP123
    Inherits Page
    Implements System.Web.UI.ICallbackEventHandler
    Protected Const EDIT_ORDER_DATE_SECURITY_CODE As Integer =  1034 
    Private Const ADD_ORDER_SECURITY_CODE As Integer =  523 
    Protected returnedString As String

    Private Sub GetName(ByVal Name As String)
        ShowMessage(Name)
    End Sub

    Private Sub GetCity(ByVal Zip As String)
        ShowMessage(Zip)
    End Sub
End Class