*

.gitignore

+/venv/
+/.idea/

main.py

+# coding=utf-8
+import datetime
+import queue
+import threading
+import time
+from threading import Thread
+
+import dash
+import dash_core_components as dcc
+import dash_html_components as html
+import paho.mqtt.client as mqtt
+from dash.dependencies import Input, Output, State
+
+external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']
+
+MQTT_SERVER = 'localhost'
+mqttc = mqtt.Client()
+
+ready_event = threading.Event()
+
+message_queue = queue.Queue()
+
+app = dash.Dash(__name__, external_stylesheets=external_stylesheets)
+app.layout = html.Div([
+    html.P("Send to scene/update"),
+    dcc.Textarea(
+        id='place-a-input-json',
+        placeholder='place-a-input-json',
+        value='{}',
+        style={'width': '100%'}
+    ),
+    html.Button('Send', id='send-place-a-update'),
+    dcc.Markdown("---"),
+    html.H3("Commands"),
+    html.Button('Place A: Model', id='send-place-a-model', style={"margin-right": "15px"}),
+    html.Button('Place A: Exit', id='send-place-a-exit', style={"margin-right": "15px"}),
+    html.Button('Place B: Model', id='send-place-b-model', style={"margin-right": "15px"}),
+    html.Button('Place B: Exit', id='send-place-b-exit', style={"margin-right": "15px"}),
+    html.H3("MQTT Log"),
+    dcc.Textarea(
+        id='mqtt-log',
+        readOnly=True,
+        rows=50,
+        style={'width': '100%', 'height': '200px'}
+    ),
+    dcc.Interval(
+        id='every-1-second',
+        interval=1000,  # in milliseconds
+        n_intervals=0
+    ),
+    html.Button("add to mqtt log", id="add-to-mqtt-log"),
+    html.Div(id='hidden-div', style={'display': 'none'})
+])
+
+
+@app.callback(
+    Output('mqtt-log', 'value'),
+    Input('every-1-second', 'n_intervals'),
+    State('mqtt-log', 'value')
+)
+def append_to_mqtt_log(_, value):
+    local_messages = []
+    while not message_queue.empty():
+        local_messages.append(message_queue.get_nowait())
+    if local_messages:
+        if value:
+            value += "\n"
+        else:
+            value = ""
+        return value + ('\n'.join(local_messages))
+    return value
+
+
+@app.callback(
+    Output('hidden-div', 'children'),
+    Input('add-to-mqtt-log', 'n_clicks'),
+)
+def button_clicked_to_add_to_mqtt_log(n_clicks):
+    if n_clicks:
+        print("button clicked")
+        message_queue.put_nowait("Button clicked " + str(n_clicks) + " times")
+    return dash.no_update
+
+
+def on_mqtt_connect(client, userdata, flags, rc, properties=None):
+    print('Connected at ' + datetime.datetime.now().isoformat())
+    ready_event.set()
+
+
+def on_mqtt_message(client, userdata, message):
+    payload = message.topic + ": " + message.payload.decode('utf-8')
+    print('Got mqtt message: ' + payload + ", userdata: " + str(userdata))
+    message_queue.put_nowait(payload)
+
+
+def on_mqtt_subscribe(client, userdata, mid, granted_qos, properties=None):
+    print("Subscribed")
+
+
+def publish_test_message():
+    time.sleep(2)
+    mqttc.publish(topic="test", payload=datetime.datetime.now().isoformat())
+
+
+if __name__ == '__main__':
+    mqttc.on_connect = on_mqtt_connect
+    mqttc.on_message = on_mqtt_message
+    mqttc.on_subscribe = on_mqtt_subscribe
+    mqttc.connect_async(MQTT_SERVER)
+    mqttc.loop_start()
+    if not ready_event.wait(2.0):  # wait 2 seconds
+        print('Could not connect to mqtt in time!')
+    mqttc.subscribe(topic='#')
+    Thread(target=publish_test_message).start()
+    app.run_server(debug=True)

requirements.txt

+paho-mqtt~=1.5.1
+dash~=1.20.0