digraph "CloudKitty's Architecture" {

    // Graph parameters
    label="CloudKitty's Internal Architecture";
    node [shape=box];
    compound=true;

    // API
    api [label="API"];

    // Orchestrator
    subgraph cluster_3 {
        label="Orchestrator";
        node[shape=none, width=1.3, height=0, label=""];
        {rank=same; o1 -> o2 -> o3 [style=invis];}
    }

    // Collector
    ceilometer [label="Ceilometer"];
    vendor [label="Vendor specific", style=dotted];
    subgraph cluster_0 {
        label="Collector";
        style=dashed;
        ceilometer -> vendor [style=invis];
    }

    // Rating
    hashmap [label="HashMap module"];
    r_others [label="Other modules...", style=dotted];
    subgraph cluster_1 {
        label="Rating engines";
        style=dashed;
        hashmap -> r_others [style=invis];
    }

    // Write Orchestrator
    w_orchestrator [label="Write Orchestrator"];
    tdb [label="Transient DB"];

    //Writers
    osrf [label="OpenStack\nReference Format\n(json)"];
    w_others [label="Other modules...", style=dotted];
    subgraph cluster_2 {
        label="Writers";
        style=dashed;
        osrf -> w_others [style=invis];
    }

    // Relations
    api -> hashmap;
    api -> r_others;
    o1 -> ceilometer [dir=both, ltail=cluster_3, lhead=cluster_0];
    o2 -> hashmap [dir=both, ltail=cluster_3, lhead=cluster_1];
    o3 -> w_orchestrator [ltail=cluster_3];
    w_orchestrator -> osrf [constraint=false];
    w_orchestrator -> w_others [style=dotted, constraint=false];
    w_orchestrator -> tdb;
}