API for reports. Preferably JSON

// This struct is returned when fetching the list of screens

screen: struct
    id: int32
    title: char[]
    machines: int32[]   // List of machines selectable for this reports
    widgets: widget[]

widget: struct
    id: int32
    title: char[]
    type: int32
    behavior: int32
        - one widget per machine
        - show all machines in one widget
        - (aggregate) sum machines
        - (aggregate) average machines
        - (aggregate) average (not 0) machines
    values: valueDef[]

valueDef: struct
    name: char[]
    format: char[]
    type: int32

// Get data for screen

screenId: int32
machines: int32[] // The subset of screen machines to fetch data for
timeStart: int32 // Unix timestamp
timeEnd: int32 // Unix timestamp

// Return value

dictionary:
    key: machineId
    value: struct
        item1: date
        item2: object[] // string, int, float