protected void registerInternalRPCService() throws StartupException {
    // Start InternalRPCService to indicate that the current DataNode can accept cluster scheduling
    registerManager.register(DataNodeInternalRPCService.getInstance());
  }
Set up RPC and protocols after DataNode is available
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/service/DataNode.java