update asynchronous example to dash 1.17.0

dash-asynchronous.py

@@ -1,12 +1,12 @@
 import dash
-from dash.dependencies import Input, Output, Event
+from dash.dependencies import Input, Output
 import dash_core_components as dcc
 import dash_html_components as html
+import logging
 
 import datetime
 import time
 
-
 class Semaphore:
     def __init__(self, filename='semaphore.txt'):
         self.filename = filename
@@ -24,10 +24,8 @@ def unlock(self):
     def is_locked(self):
         return open(self.filename, 'r').read() == 'working'
 
-
 semaphore = Semaphore()
 
-
 def long_process():
     if semaphore.is_locked():
         raise Exception('Resource is locked')
@@ -36,36 +34,36 @@ def long_process():
     semaphore.unlock()
     return datetime.datetime.now()
 
-
 app = dash.Dash()
-server = app.server
-
+app.logger.setLevel(logging.DEBUG)
 
 def layout():
     return html.Div([
         html.Button('Run Process', id='button'),
         dcc.Interval(id='interval', interval=500),
-        html.Div(id='lock'),
-        html.Div(id='output'),
+        dcc.RadioItems(
+            id='lock',
+            options=[{'label': i, 'value': i} for i in ['Running...', 'Free']]),
+        html.Div(id='output')
     ])
 
-
 app.layout = layout
 
-
 @app.callback(
-    Output('lock', 'children'),
-    events=[Event('interval', 'interval')])
-def display_status():
+    Output('lock', 'value'),
+    [Input('interval', 'n_intervals')])
+def display_status(interval):
+    app.logger.debug("display_status")
     return 'Running...' if semaphore.is_locked() else 'Free'
 
-
 @app.callback(
     Output('output', 'children'),
-    events=[Event('button', 'click')])
-def run_process():
+    [Input('button', 'n_clicks')])
+def run_process(button_input):
+    app.logger.debug("run_process")
     return 'Finished at {}'.format(long_process())
 
+app.scripts.config.serve_locally = True
 
 if __name__ == '__main__':
-    app.run_server(debug=True, processes=5)
+    app.run_server(debug=True)