node-red-contrib-opcua-compact-server 2.2.0

A maintained fork of node-red-contrib-opcua-server: a compact, programmable OPC UA server for Node-RED, with sandbox timer/error-handling fixes and ongoing production-stability improvements.

npm install node-red-contrib-opcua-compact-server

node-red-contrib-opcua-compact-server

A production-oriented, programmable OPC UA server for Node-RED. Expose any data flowing through Node-RED - from PLCs, MQTT, Modbus, databases, or anything else with a Node-RED node - as browsable OPC UA tags that any standard OPC UA client can read, subscribe to, and write back to.

Because it runs inside Node-RED, you get an OPC UA server that's driven by flows and a live tag dictionary instead of a fixed vendor configuration - useful as a lightweight, self-hosted industrial data server or gateway feeding SCADA systems, MES / manufacturing analytics platforms, historians, and HMI clients.

Highlights

• Programmable address space - expose whatever tags you want, in whatever folder structure you want (including nested folder paths), defined as plain data.
• Config-driven Tag Dictionary node - manage your tags in an editable table right in the Node-RED editor (folder, tag name, data type) instead of hand-writing code. Includes an "Import from JSON" tool to migrate an existing tag dictionary in a single paste.
• Live data with quality flagging - tags report proper OPC UA quality/status codes. If the underlying data source stops updating, tags automatically flip to a Bad status (e.g. BadNoCommunication) so clients can tell live data from stale data, then recover to Good when data resumes - the same quality-signalling behaviour industrial gateways use to indicate a device or connection is down.
• Configurable limits - session, connection-per-endpoint, and subscription limits are all set per node, so you can size the server for real client loads rather than relying on low defaults.
• No OpenSSL required - the default self-signed demo certificate is generated entirely in JavaScript at install time, with no external OpenSSL binary needed. This makes it deployable on locked-down and security-hardened Windows servers where installing OpenSSL isn't an option.
• Production-stability focused - actively maintained, with the underlying node-opcua kept current and a growing test suite. See What's different and CHANGELOG.md.

Background

This is a maintained fork of node-red-contrib-opcua-server by Klaus Landsdorf / Bianco Royal, which has been marked deprecated and is no longer actively maintained upstream. It continues that project as a new development line under new maintainership, focused on fixing production-stability issues and adding practical, deployment-focused features.

The server node is registered under a new type - opcua-compact-server-v2

• so it is distinct from the deprecated original and the two can be installed side by side. The configuration format is otherwise unchanged; see Migrating from the original below.

What's different from upstream

• Replaced the deprecated vm2 sandbox (which had critical, unpatched sandbox-escape vulnerabilities) with Node's built-in vm module.
• Fixed a sandboxed timer bug in address-space scripts where setTimeout/setInterval cleanup and error-handling never actually applied - which could leak timers and, for uncaught setInterval errors, crash the whole Node-RED process.
• Updated node-opcua to a current release (required for certificate generation to work on modern OpenSSL, among other fixes), and resolved several issues this surfaced (server-start race conditions, an unhandled-rejection crash path, a silently-ignored subscription limit, and discovery-registration configuration being ignored).
• Added new features: the Tag Dictionary config node, Bad-quality tag flagging on stale data, a per-node Namespace URI field, an External Helper Module field (load shared address-space logic from a file with no settings.js changes), startup warnings for insecure/unbounded defaults, and OpenSSL-free certificate generation.

Full detail is in CHANGELOG.md.

Core

Uses the next generation node-opcua version from Etienne Rossignon.

Install

Run the following command in your Node-RED user directory - typically ~/.node-red:

npm install node-red-contrib-opcua-compact-server

Or install it from the Node-RED editor via Manage palette → Install and search for node-red-contrib-opcua-compact-server.

Try these options on npm install to build from source if you have problems installing:

--unsafe-perm --build-from-source

Migrating from the original

Coming from the deprecated node-red-contrib-opcua-server package? Install this package (it can sit alongside the original, since it registers a distinct node type). Because the server node type changed from opcua-compact-server to opcua-compact-server-v2, existing flows do not switch over automatically - Node-RED matches nodes to flows by type, so the old node will not become this one on its own.

To migrate a flow, drop in a new Compact-Server v2 node in place of each old server node and re-enter its configuration. Every configuration field is unchanged, so the settings map across one-to-one. Once every flow has been moved over, you can uninstall the original package.

Getting started

A complete, self-contained example flow is included under examples/ (opcua-blueprint-full-example-flow.json) - import it from the Node-RED editor (menu → Import) to see the Tag Dictionary node, live data simulation, and quality flagging all working together on opc.tcp://localhost:4841, with no external infrastructure needed. See examples/opcua-blueprint-setup.md for a walkthrough.

Tags and folder structure

Define your tags in the Tag Dictionary node - one row per tag, each with a Folder, Tag name, and Data type. The dictionary is published to Node-RED flow context and turned into the OPC UA address space by the server node automatically. The helper that builds the address space ships with the package and is loaded for you - there is no file to copy or path to configure.

Folders can be nested. A Folder value may be a /-separated path, so you can lay the address space out however your site needs:

Tags sit directly under Objects, and tags sharing a folder path share the same folders. NodeIds follow the path, e.g. s=Plant.Line1.Machine1.Speed.

Reads and writes. Clients can read and subscribe to every tag. Writes are accepted too: a write updates the tag's value and is emitted from the server node's output as a WriteRequest message ({ topic: "WriteRequest", tagName, payload }), so your flow can forward it on to the real device. Whatever feeds the live data remains the source of truth - if a data source keeps refreshing a tag, it overrides a written value on its next update.

Debug

Verbose logging provides useful information when IDE or console debugging isn't possible. Start Node-RED in verbose (-v) mode:

DEBUG=opcuaCompact* node-red -v 1>Node-RED-OPC-UA-Server.log 2>&1

or on local Node-RED:

DEBUG=opcuaCompact* node red.js -v 1>Node-RED-OPC-UA-Server.log 2>&1

Security note

The auto-generated certificate is a self-signed demo certificate, and anonymous access is available for easy first-run setup. The server warns at startup when it's running with these convenience defaults. For production use, configure your own certificate and disable anonymous access.

Code Style

Prettier

Contribution

Contributions are welcome! Please open an issue or pull request on GitHub.

Happy coding!

License

MIT license. Based on the original work by Klaus Landsdorf (Bianco Royal Software Innovations), Copyright (c) 2018-2022, with fork additions Copyright (c) 2026 Nathan Rossi. See LICENSE.