© Nink AI Engineering GmbH

The Licence Was Never the Barrier

Last week I argued that the SysML v2 pilot implementation is being deliberately reshaped from a reference IDE you install into a library other people embed — the relicensing to EPL-2.0 and the refactoring to run outside Eclipse plugins being one move rather than two.

The refactoring is real, and the release notes say so in as many words. But a new VS Code extension for SysML v2 and KerML has turned up, published after both steps landed, and it is the clean test of whether anyone wants what OMG is now offering.

It does not use the pilot implementation. It is a pure TypeScript language server built on Langium, and its documentation makes a point of stating that no JDK or separate runtime is required. It takes exactly one thing from OMG: the standard model library files, verbatim.

Nor is it an outlier. Sensmetry's SysIDE is Langium and TypeScript. Eclipse SysON is a ground-up implementation of the metamodel. There are others.

So the thesis needs a correction I did not enjoy writing. Parsing-as-a-library is landing — but as several mutually incompatible libraries, none of them OMG's. The licence was never what stopped people embedding SysML v2. The JVM was, and EPL-2.0 does not remove a JVM.

Which relocates the interoperability question. If four implementations parse the same language independently, what makes them interoperable is not shared code but shared formats: the textual notation, the archive format, the standard library. Those are the artifacts to hold OMG to.

One caveat about this particular extension. It is proprietary freeware, closed source, single author, under three hundred installs — and nowhere states which version of the specification its grammar targets. For a conformance-driven standard that is not a detail. You cannot check what nobody publishes.