31 posts tagged with "tutorials"

Your robot has a camera. You are storing what it sees as one image per frame, and that works until someone asks to watch it. Then you write a script that extracts ten thousand JPEGs from storage, sorts them by timestamp, and calls ffmpeg. You write that script again the next time anyone wants thirty seconds of footage.

Storing the encoded stream removes that step. ReductStore stores H.264 chunks as time-indexed records, and the ReductVideo extension returns an MP4 you can open in a player.

If you're running Zenoh, whether as rmw_zenoh in ROS 2 or as the transport between a robot, a gateway, and the cloud, you'll eventually run into the same question:

"Where does this data actually go? I need to replay yesterday's run, debug a fault from a remote robot, and pull a few thousand frames for training."

There's plenty of material on the communication layer itself: pub/sub primitives, how Zenoh compares to DDS, multi-node setups down to a Raspberry Pi. rmw_zenoh reached Tier-1 status starting with ROS 2 Kilted Kaiju, and it's getting real attention at events like ROSCon.

What's harder to find is the next layer: what happens to a sample after it's published. Connecting a live Zenoh network to something persistent and queryable usually means working around the limits of Zenoh's existing storage options.

This post shows another way. By the end you'll have a Python publisher sending data over Zenoh, a storage backend persisting it automatically, and a query client pulling exact time ranges back out, all without a custom backend or a bridge process.

MQTT is a common choice for the communication stack in IoT and robotics applications because it is lightweight and easy to integrate. But many of those applications do not send only small JSON telemetry messages. They also publish JPEG frames, vibration waveforms, audio clips, protobuf messages, and other binary payloads that need to be stored and queried later.

This is where a regular MQTT broker or a traditional time-series database starts to fall short. Brokers are designed for message delivery, not long-term historical storage, and many databases either expect structured numeric fields or make it hard to keep large binary records tied to accurate timestamps.

In this tutorial, we will use ReductBridge to subscribe to MQTT topics and write the raw binary payloads into ReductStore with a time index. This lets you keep camera frames and sensor payloads as they are, while still querying them by time range, labels, and entry name for replay, debugging, and offline analysis.