@Override
  public void registerInTopologyHostInfo(Host host) {
    TopologyHostInfoEntity entity = topologyHostInfoDAO.findByHostname(host.getHostName());
    if(entity != null && entity.getHostEntity() == null) {
      entity.setHostEntity(hostDAO.findById(host.getHostId()));
      topologyHostInfoDAO.merge(entity);
    }
  }
Implementation which uses Ambari Database DAO and Entity objects for persistence
of topology related information.
ambari-server/src/main/java/org/apache/ambari/server/topology/PersistedStateImpl.java