function showLogin() {
   $('ajaxLogin').style.display = 'block';
}
function onSuccessfulLogin() {
   Element.hide('ajaxLogin');
   Element.hide('loginLink');
}
function authAjax() {
   Element.update('loginMessage', 'Sending request ...');
   Element.show('loginMessage');
   var form = document.ajaxLoginForm;
   var params = Form.serialize(form) + '&spring-security-redirect=/login/ajaxSuccess';
   Form.disable(form);
   new Ajax.Request(form.action, {
      method: 'POST',
      postBody: params,
      onSuccess: function(response) {
         var responseText = response.responseText || '[]';
         var json = responseText.evalJSON();
         if (json.success) {
			   Element.hide('ajaxLogin');
			   Element.hide('loginLink');
            onSuccessfulLogin();
         }
         else if (json.error) {
            Element.update('loginMessage', "<span class='errorMessage'>" + json.error + '</error>');
            Form.enable(document.ajaxLoginForm);
         }
         else {
            Element.update('loginMessage', responseText);
            Form.enable(document.ajaxLoginForm);
         }
      }
   });
}