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Things Talking to Things With MQTT

Rick Carlino

About This Talk

  • Topic
  • Target Audience
  • About You
  • About Me
  • Other Stuff

What We Will Learn

  • Sending information remotely (Arduino -> Internet)
  • Sending commands remotely
  • Getting realtime (push) notifications from devices
  • Security and Authentication
  • Dealing with offline situations

Live Demo: The Bell

What just happened?

Live Demo: FarmBot

What Can MQTT Do?

  • "Publish" sensor data using "topics"
  • "Subscribe" to user input
  • Handle disconnects
  • Handle security

What Are People Making with MQTT?

Robotics

farmbot

Telemetry / Sensor Systems

telemetry

Small Scale Hobby Projects

hobby projects

What is it?

  • Designed in 1999 at IBM. Opensourced in 2010.
  • Goals: Light weight, minimal battery loss, bandwidth.
  • MQTT is not an acronym.
  • It's a message broker, Not actually a message queue

Advantages

  • Works on Arudino, browser, desktop, mobile.
  • Optimized to save bandwidth (cellular devices)
  • Standardized
  • Standard is very compact and easy to understand
  • Well written documentation (really!)
  • Transmit anything! (JSON, XML, binary, images- whatever!)

Alternatives

  • REST (not realtime)
  • Raw TCP socket (too much coding)
  • Proprietary "platforms"

Clients

Brokers

Very easy to run your own MQTT server.

  • Mosquitto (sudo apt-get install mosquitto)
  • Mosca
  • RabbitMQ (advanced)
  • AWS IoT

Topics, Pub/Sub

  • Organize messages into "topics"
  • Kind of like a chatroom
  • Example: house/airconditioner/temp_sensors/1
  • Sensors "publish" to topics.
  • Consumers "subscribe" to get latest readings.

Topic Patterns

  • + symbol
  • / symbol
  • $ symbol
  • # symbol

EXAMPLES: /home/sensors/thermostat1, /home/sensors/#, /$SYS/#.

EXERCISE: MQTT Chat

  • Server: 67.205.153.250
  • Port: 8083
  • Username: foxbuild

Before using MQTT on a device, let's use MQTT with our laptops.

http://www.hivemq.com/demos/websocket-client/

EXERCISE: "retained" messages

(Wind turbine example)

What if no one is around to receive the message?

http://www.hivemq.com/demos/websocket-client/

Quality of Service (QoS)

3 levels:

  • At most once (0) - "unimportant" data, like live streams.
  • At least once (1) - guaranteed delivery, possible duplicates.
  • Exactly once (2) - Most resource intensive for server. Not possible on all servers!

EXERCISE: "last will" messages

What if you need to react to device failure?

http://www.hivemq.com/demos/websocket-client/

EXERCISE: MQTT for ESP

Now let's build an MQTT-enabled bell ringer.

Advanced Stuff

  • "persistent" messages (message broker style messages)
  • Last will and testament
  • QoS
  • Distinction from "real" message queues.
  • "retained" messages

Security

  • SSL
  • Shodan and other crawlers.
  • Lax security culture.
  • Malware

Available Hardware

  • ESP
  • Ardunio shields?

Extras