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_mongo_reader [label="MongoPersistReader"]
    persisters_mongo_writer [label="MongoPersistWriter"]
  }
  subgraph cluster_dbs {
    label="dbs";
    mongo [label="mongo", shape="cylinder"]
  }
  generators -> providers
  providers -> processors
  processors -> persisters_mongo_writer [label="StreamsDatum"]
  persisters_mongo_reader -> processors [label="StreamsDatum[String]"]
  mongo -> persisters_mongo_reader
  persisters_mongo_writer -> mongo
}