private void create() throws Exception {
      client =
        CuratorFrameworkFactory.builder().connectString(ensemble).sessionTimeoutMs(sessionTimeout)
          .retryPolicy(new RetryForever(1000)).canBeReadOnly(true).build();
      client.start();
      cache = new NodeCache(client, NODE);
      cache.start(true);
    }
Internal watcher that keep "data" up to date asynchronously.
hbase-examples/src/main/java/org/apache/hadoop/hbase/coprocessor/example/ZooKeeperScanPolicyObserver.java