MQTT Research

[ben8622]

Research and figure out the following:

• What is MQTT?
• How does MQTT work?
• Does MQTT work better for metrics collection than setting up devices to hit a REST API I also have to create and manage?
• Does MQTT fit into home assistant better?
• Is MQTT more reusable compared to hitting an API endpoint?

[ben8622]

Conclusion: MQTT is a lightweight messaging protocol designed for IoT devices. It works in a publisher subscriber architecture and has many useful additions out of the box like scalability and security. After some digging though, it looks like most devices that connect on home assistant are not using MQTT. There's, more likely, some combination of mDNS and pre-configured integrations. MQTT does support auto discovery though through MQTT and it looks like it can tell home-assistant what it outputs/offers so it may be worth looking into. Definitely won't be apart of the MVP, but may be worth it later. Reddit post asking for this info.

Helpful Links:

• https://mqtt.org/
• MQTT Basics https://www.hivemq.com/mqtt/
• How MQTT works http://www.steves-internet-guide.com/mqtt-works/
• Python Client https://pypi.org/project/paho-mqtt/#getting-started

MQTT stands for MQ (Message Queue) Telemetry Transport. It is the standard messaging protocol for IoT since it is an extremely lightweight way to send data from devices with relatively small footprints. Think of temperature sensors just reporting a single integer every 5 minutes. That's not even a megabyte of data a day.

MQTT is standardized by OASIS and ISO.

MQTT follows a publisher/subscriber architecture. The three main pieces being a MQTT Publisher, a MQTT Broker, and a MQTT Subscriber.

Features of MQTT:

• MQTT allows bi-direction communication so broadcasting messages to large groups is very easy
• Can supposedly scale to millions of IoT devices
• Supports encryption using TLS
• Clients can be authenticated using modern methods like OAuth
• Works even on unreliable networks
• Supports at most once messaging, at least once messaging, and exactly once messaging

Link to a python MQTT client library called paho-mqtt. Think the same client is created in C++ as well.

[ben8622]

What is MQTT?

Answered in above comment

How does MQTT work?

Answered mostly in above comment

Does MQTT work better for metrics collection than setting up devices to hit a REST API I also have to create and manage?

If I spun up my own detailed architecture it could, however I don't plan on doing that any time soon so a REST API is probably much simpler. May be worth it just for the experience, but also depends how / if I want to integrate it into Home Assistant.

Does MQTT fit into home assistant better?

Not really better but it does look like MQTT will provide a way for HomeAssistant to auto discover devices and what the device puts out (metrics and actions). I think it'd be better for a large 10+ devices setup gathering metrics.

Is MQTT more reusable compared to hitting an API endpoint?