Dash app to monitor ftp directory and plot extracted data from new files which appear isn’t working

Dash Python
1

I want to create a dash app that monitors ftp directory , extracts and plots the data in real time when a new file appears. I have created a sample app but it doesn’t work.

import dash
import plotly.graph_objects as go
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output, State
import dash_bootstrap_components as dbc

from app import app



app = dash.Dash(__name__) 


app.layout = html.Div( 
    [ 
        dcc.Graph(id = 'live-graph', animate = True), 
        dcc.Interval( 
            id = 'graph-update', 
            interval = 10000, 
            n_intervals = 0
        ), 
        html.Div(dbc.Row([
        dbc.Col(html.H2(id='check_update_div', children='check ' ))
        ]) )
    ] 
) 

@app.callback( 
    Output('check_update_div', 'children'), 
    [ Input('graph-update', 'n_intervals') ] 
) 
  
def update_graph_scatter(n): 
    
    print('one loop done ')
    
    a = monitor_extract_ftp()
    return ("this is  X {}".format(a))