Update.fs

let update (msg:Msg) model : Model*Cmd<Msg> = 
    match msg with
    | ...

    | Error exn ->
        printfn "error: %A" exn.Message
        model, Cmd.none

    | Noop _ ->
        model, Cmd.none        

    | NewHeartBeat (chargingPointID,heartbeat) -> 
        // ...

    | Send m -> model, Cmd.ofFunc (Elmish.WebSocket.send model.WebSocket) m Noop Error
    | ServerMsg Elmish.WebSocket.WebSocketMsg.Connected -> 
        { model with Connected = true }, Cmd.ofMsg (Send SendHeartBeats)
    | ServerMsg Elmish.WebSocket.WebSocketMsg.Disconnected -> { model with Connected = false }, Cmd.none
    | ServerMsg (Elmish.WebSocket.WebSocketMsg.Error e) -> 
        printfn "error: %A" e
        model, Cmd.none
    | ServerMsg (Elmish.WebSocket.WebSocketMsg.Data msg) -> 
        model, 
            match msg with
            | HeartBeat(chargingPointID,heartbeat) -> NewHeartBeat(chargingPointID,heartbeat)
            |> Cmd.ofMsg