Colca¶

A Colca tree

Colca is an MQTT broker for plants that are organised as a tree: machines at the edge, a hall or a site above them, perhaps a company on top. Every level runs the same program, colcad.

A node stores every record it accepts before anyone sees it, keeps the current value of every path, and replicates to its parent over one connection it opens itself. Commands travel down the same tree and are acknowledged back up.

Offline is normal. An edge keeps accepting data and executing commands while its uplink is gone, and sends everything in order once the link is back.
One namespace for the plant. Subscribe to colca/# at the top and you see every machine, with each level's position in the topic.
State and history from one store. Retained MQTT messages, a key-value view over HTTP and replayable streams with named cursors always agree.
No certificate authority. Nodes and machines are identified by ed25519 keys that are enrolled once. People sign in with a token from any OIDC provider.

Where to start¶

Try the demo: a tree of four nodes and two machines in containers.
Run a node on your own machine.
How Colca works is the best first read on the ideas.
chaski is the Python SDK for services that run next to a node.

Colca is licensed under the Functional Source License, Version 1.1, ALv2 Future License.