function get_http_object()
{
    var xhr; 
    try {  xhr = new ActiveXObject('Msxml2.XMLHTTP');   }

    catch (e) 
    {
        try {   xhr = new ActiveXObject('Microsoft.XMLHTTP');    }
        catch (e2) 
        {
          try {  xhr = new XMLHttpRequest();     }
          catch (e3) {  xhr = false;   }
        }
     }

    return xhr;
}

function ajax_comm( web_script , service_lambda , get_param)
{
    var request = get_http_object();
    var method = "GET";

    if(request){
            request.onreadystatechange = function() {
                service_lambda(request);
            };

        request.open(method , web_script+"?"+get_param , true);
        request.send(null);
        return request; //set callback
    }
    return false; //somethin is wrong
}