Mqtt notes

Notes on MQTT . . .

*  https://thenewstack.io/mqtt-protocol-iot/

Unsorted references to MQTT:

# https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/samples/net/mqtt_publisher/README.html
# https://www.hivemq.com/blog/mqtt-essentials-part2-publish-subscribe/
# https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/samples/index.html
# https://www.circuito.io/blog/arduino-code/
# https://www.hivemq.com/blog/mqtt-essentials-part-7-persistent-session-queuing-messages/
# https://www.hivemq.com/blog/mqtt-essentials-part-3-client-broker-connection-establishment/

# https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.6.1/nrf/examples.html
# https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.6.1/nrf/ug_tfm.html#ug-tfm
# https://ci-builds.trustedfirmware.org/static-files/UxIoKYsDyPQ0ojvJOv9EX6-hZNDZd6IPGfcm05Bk1b0xNjM3MTA4NjMxODUxOjk6YW5vbnltb3VzOmpvYi90Zi1tLWJ1aWxkLWRvY3MtbmlnaHRseS9sYXN0U3RhYmxlQnVpbGQvYXJ0aWZhY3Q=/trusted-firmware-m/build/docs/user_guide/html/index.html

Nordic AWS FOTA example:

# https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.6.1/nrf/samples/nrf9160/aws_fota/README.html