code: public static boolean validSchema(URI uri) throws IOException {
      LOG.trace("Checking schema {}", uri.toString());
      String hostName = Utils.getHost(uri);
      LOG.trace("Got hostname as {}", hostName);
      int i = hostName.lastIndexOf(".");
      if (i < 0) {
        return false;
      }
      String service = hostName.substring(i + 1);
      LOG.trace("Got service as {}", service);
      if (service.isEmpty() || service.contains(".")) {
        return false;
      }
      return true;
    }
docs: Test if hostName of the form container.service
  
  @param uri schema URI
  @return true if hostName of the form container.service
  @throws IOException if error