Zenoh

Install Zenoh Middleware

Zenoh is a pub/sub/query protocol unifying data in motion, data at rest and computations. You need two pieces - the eclipse-zenoh python library and the Zenoh daemon (zenohd). Your Python project needs eclipse-zenoh, which is already added to OM1's pyproject.toml.

Mac

Install the Zenoh router:

$ brew tap eclipse-zenoh/homebrew-zenoh
$ brew install zenoh

Linux

Install the Zenoh router:

$ echo "deb [trusted=yes] https://download.eclipse.org/zenoh/debian-repo/ /" | sudo tee -a /etc/apt/sources.list > /dev/null
$ sudo apt update
$ sudo apt install zenoh

Starting/testing the Router

In a separate terminal window, start the router:

# inside OM1
zenohd -c robot_storage.json5

Testing:

zenohd --help

Installing the Persistent Backend

See https://github.com/eclipse-zenoh/zenoh-backend-filesystem?tab=readme-ov-file#how-to-install-it

On Mac, you might need to allow libzenoh_backend_fs.dylib to run via Privacy and Security. Just try to run it separately - e.g. via the terminal and then approve the various popup messages. Once you have run libzenoh_backend_fs.dylib once, it will be cached and then zenoh can find it the next time. This is good, but can be confusing if you are trying to upgrade libzenoh_backend_fs.dylib but it keeps using an older cached version.

The RocksDB database is where ever you set the path to:

export ZENOH_BACKEND_FS_ROOT=$PWD/zenohdb/

The RocksDB version: 9.9.3 is set up at ZENOH_BACKEND_FS_ROOT, where it creates a system of folders. For example, a PUT to /robot/audio creates a file at /zenohdb/robot/audio, which then contains the most recent value of the robot/audio key.

Using the REST API at ::9500

You can use curl to publish and query the latest keys/values:

# Put values that will be stored under ${ZENOH_BACKEND_FS_ROOT}/robot
curl -X PUT -d "HELLO WORLD" http://localhost:9500/robot
curl -X PUT -d "HELLO WORLD A" http://localhost:9500/robot/audio

# Retrieve the values
curl http://localhost:9500/robot
curl http://localhost:9500/robot/audio

To be clear, the system only saves the most recent key/value pair.