[TTN v3] Using MQTT to retrieve TTN aplication data on the fly - l0ad/ubpe-valence-LoRa GitHub Wiki
This section describes how to remotely retrieve live application data, connecting to TTN MQTT broker.
This requires to set up TTN MQTT integration, and either using a general-purpose MQTT client or writing an ad'hoc one.
Setting up MQTT integration
From application home page, select Integrations (from left-sidebar) and then MQTT:
Then select Generate API Key (iut-valence-ubpe-hao@ttn/ API Key will further be used as MQTT client credentials):
⚠️ Immediately copy and save the API Key since it couldn't be further retrieved!
To see all API keyx, select API Keys (from left-sidebar):
Selcting an API key allows to give it a more friendly name, and to tune access rights (here limitedf to read application data):
Retrieving application devices data using a general purpose MQTT client
The client used here is MQTT Explorer, an open source MQTT client that can be found here.
Once launched, configure a new connection by filling fields with relevant information:
⚠️ Certificate validation has to be disable and user/password must be filled with credentials obtained previously while configuration TTN MQTT integration.
Then, establish connection and wait for incoming messages to be retrieved:
💡 Incoming device data are published on a topic whose name is like v3/username/devices/devide-id/up (here v3/iut-valence-ubpe-hao@ttn/devices/eui-0000000000000001/up), and retrieved as a JSON object:
{
"end_device_ids":{
"device_id":"eui-0000000000000001",
"application_ids":{
"application_id":"iut-valence-ubpe-hao"
},
"dev_eui":"0000000000000001",
"dev_addr":"260B1D3D"
},
"correlation_ids":[
"as:up:01GSCRFBNA0B950E6Q9NNR2013",
"gs:conn:01GSAQRDR94P67SK26DBQ5PREA",
"gs:up:host:01GSAQRDRCAF355XJT6ZK6M3Z3",
"gs:uplink:01GSCRFBEW7JJEMDY1GWRC9233",
"ns:uplink:01GSCRFBEWSRYW0GX07K6V249B",
"rpc:/ttn.lorawan.v3.GsNs/HandleUplink:01GSCRFBEWJ756GYMNFAMG3MX5",
"rpc:/ttn.lorawan.v3.NsAs/HandleUplink:01GSCRFBN9ERVQCPGVW9GVX4M1"
],
"received_at":"2023-02-16T09:21:49.737776462Z",
"uplink_message":{
"f_port":1,
"f_cnt":73,
"frm_payload":"AgC4HoVBAAAoQg==",
"decoded_payload":{
"humidity":42,
"sys_time":2,
"temperature":16.6
},
"rx_metadata":[
{
"gateway_ids":{
"gateway_id":"iut-valence-ttn-gw-02",
"eui":"B827EBFFFEBB2805"
},
"time":"2023-02-16T09:21:49.525169362Z",
"timestamp":3769747748,
"rssi":-95,
"channel_rssi":-95,
"snr":7,
"uplink_token":"CiMKIQoVaXV0LXZhbGVuY2UtdHRuLWd3LTAyEgi4J+v//rsoBRCkkseFDhoMCK3rt58GEMKT1/0BIKDp5rPbwA8=",
"channel_index":2,
"received_at":"2023-02-16T09:21:49.532007362Z"
}
],
"settings":{
"data_rate":{
"lora":{
"bandwidth":125000,
"spreading_factor":9,
"coding_rate":"4/5"
}
},
"frequency":"868500000",
"timestamp":3769747748,
"time":"2023-02-16T09:21:49.525169362Z"
},
"received_at":"2023-02-16T09:21:49.532956003Z",
"consumed_airtime":"0.205824s",
"network_ids":{
"net_id":"000013",
"tenant_id":"ttn",
"cluster_id":"eu1",
"cluster_address":"eu1.cloud.thethings.network"
}
}
}
⚠️ Only new MQTT messages can be retrieved, older are lost.
Retrieving application devices data using a Python script
💡 The following Python3 script acts as a MQTT client that connects to TTN MQTT server (with same credentials as previous) and subscribe to application devices uplink topic. Then, it saves timestamped raw JSON payloads in a file, and outputs application-level decoded payload (here, fake sensor values)
⚠️ This script relies on paho-mqtt library (that can be easily installed using pip)
# Dump all device uplink messages in a file
import paho.mqtt.client as mqtt
from datetime import datetime
import json
import os
MQTT_SERVER = "eu1.cloud.thethings.network"
MQTT_PORT = 1883
MQTT_CONNECTION_TIMEOUT = 60
MQTT_CLIENT_NAME = "ttn-client-dump"
#########################################################
# TO BE UPDATED WRT APP AND API KEY
#########################################################
TTN_APP_NAME = "iut-valence-ubpe-hao@ttn"
TTN_USER = "iut-valence-ubpe-hao@ttn"
TTN_PWD = "NNSXS.THIS-IS-NOT-THE-PWD-YOU-ARE-LOOKING-FOR"
#########################################################
# Callback for when the client receives a CONNACK response from the server.
def on_connect(client, userdata, flags, rc):
if rc != 0:
print("Unable to connect (resultcode " + rc+ ")")
quit()
print("Connected, waiting for messages...")
client.subscribe('v3/' + TTN_APP_NAME + '/devices/+/up')
def save_payload(payload, time, path):
with open(path, 'a') as dump_file:
dump_file.write("------------------\n")
dump_file.write(time + "\n")
dump_file.write("------------------\n")
dump_file.write(payload+"\n")
dump_file.close()
# Callback for when a PUBLISH message is received from the server.
def on_message(client, userdata, msg):
try:
time_str = datetime.now().strftime("%d-%m-%y_%Hh%Mm%Ss")
print("[received] at " + time_str)
json_payload = json.loads(msg.payload.decode('utf-8'))
formatted_payload = json.dumps(json_payload, indent=4)
print(formatted_payload)
save_payload(formatted_payload, time_str, PATH)
print("[saved]")
app_decoded_payload = json_payload["uplink_message"]["decoded_payload"]
print("sys_time: " + str(app_decoded_payload["sys_time"]))
print("temperature: " + str(app_decoded_payload["temperature"]) + " °C")
print("humidity: " + str(app_decoded_payload["humidity"]) + " %")
print("[decoded]")
except Exception as exception:
print("[malformed]")
print("---")
print(exception)
print("---")
pass
now = datetime.now()
current_time = now.strftime("%d-%m-%y_%Hh%M")
PATH = current_time + ".dump"
print("TTN application devices uplink dumper started!")
print("Saving in " + PATH)
with open(PATH, 'w') as fp:
pass
client = mqtt.Client(MQTT_CLIENT_NAME);
client.username_pw_set(TTN_USER, TTN_PWD)
client.on_connect = on_connect
client.on_message = on_message
client.connect(MQTT_SERVER, MQTT_PORT, 60)
# Blocking call that processes network traffic, dispatches callbacks and
# handles reconnecting.
# Other loop*() functions are available that give a threaded interface and a
# manual interface.
client.loop_forever()
Below shows how standard output looks like when executing the script:
TTN application devices uplink dumper started!
Saving in 17-02-23_14h16.dump
Connected, waiting for messages...
[received] at 17-02-23_14h16m43s
{
"end_device_ids": {
"device_id": "eui-0000000000000001",
"application_ids": {
"application_id": "iut-valence-ubpe-hao"
},
"dev_eui": "0000000000000001",
"dev_addr": "260B1D3D"
},
"correlation_ids": [
"as:up:01GSFRA5X257A7XPCM47SSJ2V3",
"gs:conn:01GSAQRDR94P67SK26DBQ5PREA",
"gs:up:host:01GSAQRDRCAF355XJT6ZK6M3Z3",
"gs:uplink:01GSFRA5PHMSBH8BSEYGHN967Q",
"ns:uplink:01GSFRA5PJJ5RM1TMNTSBPA5H5",
"rpc:/ttn.lorawan.v3.GsNs/HandleUplink:01GSFRA5PJ97N01AJZ71M23MYR",
"rpc:/ttn.lorawan.v3.NsAs/HandleUplink:01GSFRA5X120A5YCFQ56Q4DGDN"
],
"received_at": "2023-02-17T13:16:43.298133030Z",
"uplink_message": {
"f_port": 1,
"f_cnt": 97,
"frm_payload": "AgC4HoVBAAAoQg==",
"decoded_payload": {
"humidity": 42,
"sys_time": 2,
"temperature": 16.6
},
"rx_metadata": [
{
"gateway_ids": {
"gateway_id": "iut-valence-ttn-gw-02",
"eui": "B827EBFFFEBB2805"
},
"time": "2023-02-17T13:16:43.066329449Z",
"timestamp": 1184048548,
"rssi": -101,
"channel_rssi": -101,
"snr": 5,
"uplink_token": "CiMKIQoVaXV0LXZhbGVuY2UtdHRuLWd3LTAyEgi4J+v//rsoBRCky8y0BBoLCLv8vZ8GEN3y1CogoJGs9rqtJg==",
"channel_index": 1,
"received_at": "2023-02-17T13:16:43.073901749Z"
}
],
"settings": {
"data_rate": {
"lora": {
"bandwidth": 125000,
"spreading_factor": 9,
"coding_rate": "4/5"
}
},
"frequency": "868300000",
"timestamp": 1184048548,
"time": "2023-02-17T13:16:43.066329449Z"
},
"received_at": "2023-02-17T13:16:43.090406034Z",
"consumed_airtime": "0.205824s",
"network_ids": {
"net_id": "000013",
"tenant_id": "ttn",
"cluster_id": "eu1",
"cluster_address": "eu1.cloud.thethings.network"
}
}
}
[saved]
sys_time: 2
temperature: 16.6 °C
humidity: 42 %
[decoded]