EdgeLinkd
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Compatibility

What Node-RED compatible means for EdgeLinkd, and what to check before migrating flows.

EdgeLinkd is a Node-RED compatible runtime, not a Node-RED clone. It targets embedded and resource-constrained deployments, and that shapes the compatibility contract in both directions.

The contract

What EdgeLinkd ships behaves like Node-RED. For every node, option and property type it offers, the observable behaviour — message semantics, errors and status, the editor contract — must match Node-RED v4.0.9, the pinned upstream release. The ported spec tests assert exactly that.

What does not fit the budget is not offered. A feature whose memory or binary-size cost is too high for the target hardware, or that depends on the Node.js ecosystem, is out of scope by design. That is a decision, not a bug and not a pending TODO.

Nothing is faked. Anything the editor can produce must either work, or fail loudly and at once: a deploy error, a node error or status, or NotSupported. Options are never accepted and then silently ignored.

Reading the status

  • The project README tracks feature-level status. A check mark means the feature passes the integration tests ported from Node-RED.
  • The live spec coverage page compares the ported tests with upstream describe() and it() titles by release, node, and individual test.
  • An upstream test marked @pytest.mark.skip(reason=...) records a deliberate scope decision; its reason names the unsupported feature.

Before migrating flows

  1. Inventory your node types. edgelinkd list prints every node type compiled into your binary; compare it with the types used in your flows.json.
  2. Replace npm-only nodes. Third-party nodes from the npm ecosystem do not run on EdgeLinkd. Move their logic to core nodes or a function node, or implement a Rust node plug-in.
  3. Review function nodes. Code runs in QuickJS, not Node.js:
    • there is no Node.js Buffer — RED.util.ensureBuffer() returns a Uint8Array;
    • require() and npm modules are unavailable;
    • RED.util.prepareJSONataExpression() and evaluateJSONataExpression() fail with NOT_SUPPORTED, because JSONata belongs to the Rust runtime;
    • RED.util.evaluateNodeProperty(v, "date") with a format string fails with NOT_SUPPORTED, as the sandbox has no moment.
  4. Check JSONata expressions. $moment() is not available; an expression that calls it fails with an error instead of producing a value.
  5. Deploy and watch. Unsupported configuration surfaces at deploy time or as node status — never silently.

Reporting gaps

If a supported node behaves differently from Node-RED v4.1.15, that is a bug. Please open an issue with a minimal flows.json that reproduces it.