function ExecuteService(params, url, callbackSuccess, callbackError)
  {
    $.ajax({
     type: "POST",
     url: url,
     contentType: "text/xml; charset=utf-8",
     dataType: "xml",
     data: params,
     success: callbackSuccess,
     error: callbackError
    });                    
  }
  function Check(callbackResult, callbackError)
  {               
      var params = "{}";
      ExecuteService(
        params,
        "ws.asmx/HelloWorld2",
        callbackResult,
        callbackError
      );   
  }