The big picture

Original graph source:

style=filled;
color=lightgrey;
node [shape=box, color=purple ];
rankdir=LR;
resolution = "75";


subgraph cluster_0 {
    style=filled;
    color=lightgrey;
    node [style=filled,color=white];
    "FusionInventory for GLPI" -> "GLPI engine" -> "DB";
    label = "GLPI";
}

subgraph cluster_1 {

    subgraph cluster_4 {

        color=gainsboro;
        "Local Inventory" -> "Agent" -> "FusionInventory for GLPI";
        "ESX Inventory" -> "Agent";
        "Network Inventory" -> "Agent";
        "Agent" -> "Deploy";
        label = "FusionInventory Agent";
    }

    style=filled;
    color=lightgrey;
    node [style=filled,color=white];
    "dmidecode" -> "Local Inventory";
    "dpkg" -> "Local Inventory";
    "registry" -> "Local Inventory";
    "rpm" -> "Local Inventory";
    "WMI" -> "Local Inventory";
    "dmidecode" -> "Local Inventory";
    "PCI info" -> "Local Inventory";
    "USB info" -> "Local Inventory";
    "virtual machines" -> "Local Inventory";
    "more" -> "Local Inventory";
    "Deploy" -> "set some configuration";
    "Deploy" -> "add software";
    label = "Computer(s)";
}

subgraph cluster_2 {
    style=filled;
    color=lightgrey;
    node [style=filled,color=white];
    "vCenter1" -> "ESX Inventory";
    "esx4" -> "ESX Inventory";

    "esx1" -> "vCenter1";
    "esx2" -> "vCenter1";
    "esx3" -> "vCenter1";
    "vm1" -> "esx1";
    "vm2" -> "esx2";
    "vm3" -> "esx2";
    "vm4" -> "esx3";
    "vm5" -> "esx3";
    "vm6" -> "esx4";
    label = "VMware API";
}

subgraph cluster_3 {
    style=filled;
    color=lightgrey;
    node [style=filled,color=white];
    "printer 1" -> "Network Inventory";
    "printer 2" -> "Network Inventory";
    "switch 1" -> "Network Inventory";
    "unknown device" -> "Network Inventory";
    label = "Networks";
}