What is MQTT?
MQTT (Message Queuing Telemetry Transport) is a lightweight messaging protocol that lets devices talk to each other over the internet. It’s designed for simple, low-bandwidth connections, making it perfect for things like sensors and smart gadgets.
Let's break it down
- Message: a small piece of data (like a temperature reading).
- Queuing: the system stores messages temporarily until they can be delivered.
- Telemetry: remote measurement and reporting of data.
- Transport: the method used to move the data from one place to another.
- Lightweight: uses very little data and processing power, so it works on tiny devices and slow networks.
Why does it matter?
Because it lets everyday objects-like a thermostat or a farm sensor-send information quickly and reliably without needing a big, expensive internet connection. This makes building smart, connected systems affordable and easy.
Where is it used?
- Home automation: smart lights, thermostats, and security cameras talk to a central hub.
- Industrial monitoring: machines on a factory floor send status updates to a control system.
- Agriculture: soil moisture sensors report data to a cloud dashboard for irrigation control.
- Vehicle fleets: GPS trackers publish location data to a management platform.
Good things about it
- Very low bandwidth usage, ideal for slow or costly networks.
- Simple to implement; many libraries exist for most programming languages.
- Supports reliable delivery with three quality-of-service levels (at most once, at least once, exactly once).
- Works well with many devices simultaneously through a publish/subscribe model.
- Open standard, free to use without licensing fees.
Not-so-good things
- Security isn’t built-in; you need to add TLS or other measures yourself.
- Limited message size (typically up to 256 KB), which can be restrictive for large data.
- Relies on a central broker; if the broker goes down, communication stops unless you add redundancy.
- Not suited for high-throughput, real-time video or large file transfers.