SangamAngre SangamAngre - 6 months ago 38
Python Question

How to troubleshoot mqtt and AWS iot

I am newbie to AWS IoT and MQTT as well. I am trying with simple example to read payload from AWS and publish payload to AWS. I am able to read payload on device but not able to publish. When I update shadow state from AWS console my raspberry pi able to receive the message but when I am publishing nothing happening. Not even state is changing on AWS console.

Code is attached. Please suggest.

def on_connect(mqttc, obj, flags, rc):
if rc==0:
print ("Subscriber Connection status code: "+str(rc)+" | Connection status: successful")
elif rc==1:
print ("Subscriber Connection status code: "+str(rc)+" | Connection status: Connection refused")

def on_subscribe(mqttc, obj, mid, granted_qos):
print("Subscribed: "+str(mid)+" "+str(granted_qos)+"data"+str(obj))

def on_message(mqttc, obj, msg):
print("Received message from topic: "+msg.topic+" | QoS: "+str(msg.qos)+" | Data Received: "+str(msg.payload))

def on_publish(client, userdata, mid):
print("Message is published")

def first_message():
data = {} data['r'] = 2 data['g'] = 255 data['b'] = 95 data2 = {} data2['color'] = data data3 = {} data3['reported'] = data2 data4 = {}
data4['state'] = data3 json_data = json.dumps(data4) print(str(json_data))
(rc, mid) = mqttc.publish("$aws/things/thirdthing/shadow/update/", str(json_data), 1)

mqttc = mqtt.Client(client_id="thirdthing1")
mqttc.on_connect = on_connect
mqttc.on_subscribe = on_subscribe
mqttc.on_message = on_message
mqttc.on_publish = on_publish
mqttc.connect("", port=8883) #AWS IoT service hostname and portno
mqttc.subscribe("$aws/things/thirdthing/shadow/update/#", qos=1) #The names of these topics start with $aws/things/thingName/shadow."


Ok I solved this on myself.

Error in above code is json data formalization which I was sending. If I replace first_message() function with given code then this example works perfectly.

def first_message():
    payload = json.dumps({

    mqttc.publish("$aws/things/thirdthing/shadow/update", payload)