digraph sample_boot {
  node [shape = square];
  AMQP;
  "Event Processing + Scheduler";
  Nova;
  Neutron;

  node [shape = circle];

  AMQP -> "Event Processing + Scheduler";
  subgraph clusterrug {
      "Event Processing + Scheduler" -> "Worker 1";
      "Event Processing + Scheduler" -> "Worker ...";
      "Event Processing + Scheduler" -> "Worker N";

      "Worker 1" -> "Thread 1"
      "Worker 1" -> "Thread ..."
      "Worker 1" -> "Thread N"
  }

  "Thread 1" -> "Service VM 1";
  "Thread 1" -> "Service VM ..." [ label = "Appliance REST API" ];
  "Thread 1" -> "Service VM N";

  "Thread 1" -> "Nova" [ label = "Nova API" ];
  "Thread 1" -> "Neutron" [ label = "Neutron API" ];
}