.. zephyr:code-sample:: mqtt-sn-publisher
:name: MQTT-SN publisher
:relevant-api: mqtt_sn_socket
Send MQTT-SN PUBLISH messages to an MQTT-SN gateway.
Overview
********
`MQTT <http://mqtt.org/>`_ (MQ Telemetry Transport) is a lightweight
publish/subscribe messaging protocol optimized for small sensors and
mobile devices.
MQTT-SN can be considered as a version of MQTT which is adapted to
the peculiarities of a wireless communication environment. While MQTT
requires a reliable TCP/IP transport, MQTT-SN is designed to be usable
on any datagram-based transport like UDP, ZigBee or even a plain UART
(with an additional framing protocol).
The Zephyr MQTT-SN Publisher sample application is an MQTT-SN v1.2
client that sends MQTT-SN PUBLISH messages to an MQTT-SN gateway.
It also SUBSCRIBEs to a topic.
See the `MQTT-SN v1.2 spec`_ for more information.
.. _MQTT-SN v1.2 spec: https://www.oasis-open.org/committees/download.php/66091/MQTT-SN_spec_v1.2.pdf
The source code of this sample application can be found at:
:zephyr_file:`samples/net/mqtt_sn_publisher`.
Requirements
************
- Linux machine
- MQTT-SN gateway, like Eclipse Paho
- Mosquitto server: any version that supports MQTT v3.1.1. This sample
was tested with mosquitto 1.6.
- Mosquitto subscriber
- LAN for testing purposes (Ethernet)
Build and Running
*****************
Currently, this sample application only supports static IP addresses.
Open the :file:`prj.conf` file and set the IP addresses according
to the LAN environment.
You will also need to start an MQTT-SN gateway. With Paho, you can either
build it from source - see `PAHO MQTT-SN Gateway`_ - or run an unofficial
docker image, like `kyberpunk/paho`_.
.. _PAHO MQTT-SN Gateway: https://www.eclipse.org/paho/index.php?page=components/mqtt-sn-transparent-gateway/index.php
.. _kyberpunk/paho: https://hub.docker.com/r/kyberpunk/paho
On your Linux host computer, open 3 terminal windows. At first, start mosquitto:
.. code-block:: console
$ sudo mosquitto -v -p 1883
Then, in another window, start the gateway, e.g. by using docker:
.. code-block:: console
$ docker run -it -p 10000:10000 -p 10000:10000/udp --name paho -v $PWD/gateway.conf:/etc/paho/gateway.conf:ro kyberpunk/paho
Then, locate your zephyr directory and type:
.. zephyr-app-commands::
:zephyr-app: samples/net/mqtt_sn_publisher
:board: native_sim_64
:goals: run
:compact:
Optionally, use any MQTT explorer to connect to your broker.
Sample output
=============
This is the applications output:
.. code-block:: console
WARNING: Using a test - not safe - entropy source
*** Booting Zephyr OS build zephyr-v3.2.0-279-gc7fa387cea81 ***
[00:00:00.000,000] <inf> net_config: Initializing network
[00:00:00.000,000] <inf> net_config: IPv4 address: 172.18.0.20
[00:00:00.000,000] <inf> mqtt_sn_publisher_sample: MQTT-SN sample
[00:00:00.000,000] <inf> mqtt_sn_publisher_sample: Network connected
[00:00:00.000,000] <inf> mqtt_sn_publisher_sample: Waiting for connection...
[00:00:00.000,000] <inf> mqtt_sn_publisher_sample: Connecting client
[00:00:00.510,000] <inf> net_mqtt_sn: Decoding message type: 5
[00:00:00.510,000] <inf> net_mqtt_sn: Got message of type 5
[00:00:00.510,000] <inf> net_mqtt_sn: MQTT_SN client connected
[00:00:00.510,000] <inf> mqtt_sn_publisher_sample: MQTT-SN event EVT_CONNECTED
[00:00:01.020,000] <inf> net_mqtt_sn: Decoding message type: 19
[00:00:01.020,000] <inf> net_mqtt_sn: Got message of type 19
[00:00:10.200,000] <inf> mqtt_sn_publisher_sample: Publishing timestamp
[00:00:10.200,000] <inf> net_mqtt_sn: Registering topic
2f 75 70 74 69 6d 65 |/uptime
[00:00:10.200,000] <inf> net_mqtt_sn: Can't publish; topic is not ready
[00:00:10.710,000] <inf> net_mqtt_sn: Decoding message type: 11
[00:00:10.710,000] <inf> net_mqtt_sn: Got message of type 11
[00:00:10.710,000] <inf> net_mqtt_sn: Publishing to topic ID 14
[00:00:20.400,000] <inf> mqtt_sn_publisher_sample: Publishing timestamp
[00:00:20.400,000] <inf> net_mqtt_sn: Publishing to topic ID 14
This is the output from the MQTT-SN gateway:
.. code-block:: console
20221024 140210.191 CONNECT <--- ZEPHYR 0C 04 04 01 00 3C 5A 45 50 48 59 52
20221024 140210.192 CONNECT ===> ZEPHYR 10 12 00 04 4D 51 54 54 04 02 00 3C 00 06 5A 45 50 48 59 52
20221024 140210.192 CONNACK <=== ZEPHYR 20 02 00 00
20221024 140210.192 CONNACK ---> ZEPHYR 03 05 00
20221024 140210.643 SUBSCRIBE 0001 <--- ZEPHYR 0C 12 00 00 01 2F 6E 75 6D 62 65 72
20221024 140210.648 SUBSCRIBE 0001 ===> ZEPHYR 82 0C 00 01 00 07 2F 6E 75 6D 62 65 72 00
20221024 140210.660 SUBACK 0001 <=== ZEPHYR 90 03 00 01 00
20221024 140210.661 SUBACK 0001 ---> ZEPHYR 08 13 00 00 0D 00 01 00
20221024 140220.338 REGISTER 0002 <--- ZEPHYR 0D 0A 00 00 00 02 2F 75 70 74 69 6D 65
20221024 140220.348 REGACK 0002 ---> ZEPHYR 07 0B 00 0E 00 02 00
20221024 140220.848 PUBLISH <--- ZEPHYR 0C 0C 00 00 0E 00 00 31 30 32 30 30
20221024 140220.850 PUBLISH ===> ZEPHYR 30 0E 00 07 2F 75 70 74 69 6D 65 31 30 32 30 30
20221024 140230.539 PUBLISH <--- ZEPHYR 0C 0C 00 00 0E 00 00 32 30 34 30 30
20221024 140230.542 PUBLISH ===> ZEPHYR 30 0E 00 07 2F 75 70 74 69 6D 65 32 30 34 30 30
2cadcb3df4