@Override
  public void initTProcessor()
      throws ClassNotFoundException,
          IllegalAccessException,
          InstantiationException,
          NoSuchMethodException,
          InvocationTargetException {
    impl =
        (IClientRPCServiceWithHandler)
            Class.forName(IoTDBDescriptor.getInstance().getConfig().getRpcImplClassName())
                .getDeclaredConstructor()
                .newInstance();
    initSyncedServiceImpl(null);
    processor = new ProcessorWithMetrics(impl);
  }
A service to handle RPC request from client.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/service/ExternalRPCService.java