digraph g {
  graph [compound = true];
  //presentation
  splines = true;
  overlap = false;
  rankdir = TB;
  generators [label="generators", shape="circle"];
  providers [label="providers", shape="circle"];
  processors [label="processors", shape="circle"];
  subgraph cluster_persisters {
    label="persisters";
    persisters_hdfs_reader [label="WebHdfsPersistReader"]
    persisters_hdfs_writer [label="WebHdfsPersistWriter"]
  }
  subgraph cluster_dbs {
    label="dbs";
    hdfs [label="hdfs", shape="tab"]
  }
  generators -> providers
  providers -> processors
  processors -> persisters_hdfs_writer [label="StreamsDatum"]
  persisters_hdfs_reader -> processors [label="StreamsDatum"]
  hdfs -> persisters_hdfs_reader
  persisters_hdfs_writer -> hdfs
}