Glossary

The terms this guide uses, collected in one place. Each is explained in the chapter that leans on it; these are the short versions.

Admin API — the HTTP interface behind the editor: listing and deploying flows, firing inject buttons, logging in. The lab drove Node-RED through it; anything the editor can do, it can do.

adminAuth — the settings block that puts a username and password on the editor and Admin API.

Broker — the MQTT server that receives published messages and hands them to subscribers. Node-RED is a client of one, never the broker itself.

Config node — a shared, behind-the- scenes node describing a connection (an MQTT broker, a database) once, for many flow nodes to point at.

Context — Node-RED's notepad: node-, flow-, and global-scoped values kept between messages. In memory by default; a file-backed store can make it survive restarts.

credentialSecret — the passphrase in settings that encrypts the flows' stored credentials. Lose it, lose them.

Deploy — the act of making the drawn flows live. Until Deploy, edits are a sketch.

Flow — one job drawn as nodes on a tab; also the tab itself, and the JSON that describes it.

Function node — the node that holds JavaScript for the logic the configured nodes can't express.

Inject node — the button (and timer) that starts a message by hand or on a schedule.

Message (msg) — the object that travels the wires. Its payload is the point; its topic is a label; its _msgid is Node-RED's stamp.

MQTT — the publish/subscribe messaging protocol of small devices; this series' MQTT guide is the deep dive.

Node — one box on the canvas: an input, a processing step, or an output. Comes from the core set or a community package installed into the palette.

Palette — the editor's left-hand library of available nodes, and the manager for installing more.

Payload — msg.payload: the data a message is about, whatever type the last node left it as.

Topic — MQTT's address for a message (porch/light), and by borrowing, msg.topic on any message.

User directory — the folder (~/.node-red by default) holding flows, settings, and credentials. It is, for backup purposes, the whole kingdom.

Wire — a connection between nodes. A message sent travels to every node wired from that output.