code: public static String getIdOfTarballFromUrl(String url){
          String nameOfTarballResource=getTarballResourceNameFromUrl(url);
          return nameOfTarballResource.substring(0,nameOfTarballResource.lastIndexOf("."));
      }
docs: Return the id of the resource pointed by the url without extension
  E.g. http://example.com/resource.tar return resource
  @param url
  @return