CIM/RDF Lens

A VS Code extension that makes visible, inside RDF/XML files, which objects point at one another. The relationship lives in the UUID:

<cim:Breaker rdf:about="urn:uuid:...c0de00000001">        <- definition
...
<cim:Measurement.PowerSystemResource rdf:resource="urn:uuid:...c0de00000001"/>
                                                          ^- reference to it

The extension registers .rdf, .rdfs and .owl with the built-in XML language -- so these files also get XML syntax highlighting, which VS Code does not otherwise offer for them.

Both get the same colour -- as a bar in the gutter (the code margin) and as a coloured underline beneath the UUID itself. The XML syntax highlighting stays untouched: no token is recoloured, no background is tinted, only the underline is added.

How to read the bars

The bars show only the nesting, and they run through the whole block: one bar per hierarchy level, root on the left, then descending to the right, the outermost one being the block itself. Every line of a block carries the same sequence -- no bar starts or ends in the middle of a block.

All bars are fully opaque. An ancestor bar has exactly the colour of the block it belongs to; that is the only way it stays recognisable. A faded colour mixes with the editor background and becomes a different hue from the original -- losing precisely the mapping that matters here. If you want it anyway, set cimRdfLens.ancestorOpacity.

The column width applies document-wide, so that equal levels line up under one another across all lines.

Underlines

Where a single line points is told not by the bars but by the underline: every UUID in the text is underlined in the colour of the object it means -- the rdf:about just as much as every rdf:resource that points at it. Only the identifier is underlined, not the urn:uuid: prefix and not the quotation marks. In leistungsschalter.rdf that is 47 spots; the Breaker UUID, for instance, appears seven times and is underlined the same way all seven times.

This way each device has exactly one job: bars = hierarchy across the whole block, underline = the reference in this line. The unitSymbol line is the counter-test: UnitSymbol.A points out of the file and therefore gets no underline.

Can be switched off via cimRdfLens.underlineIds.

cimRdfLens.markReferences additionally shows a single bar on rdf:resource lines. The default is off: it breaks the continuous block bars and merely repeats what the underline already shows.

How the hierarchy is built

An rdf:resource edge points from child to parent: AnalogLimit names its LimitSet, the set its Measurements, the measurement its PowerSystemResource. Follow the edges and you walk to the root; an object with no resolvable reference is a root.

That yields a DAG, not a tree -- cim:Analog hangs off the Terminal and directly off the equipment. The bar order needs a single path, so the longest one wins: Breaker > Terminal > Analog rather than Breaker > Analog. That way you see the deepest nesting and not the one that happened to come first. Cycles are detected and capped.

In addition

• Hover over a UUID: class, name, the whole hierarchy with colour swatches, the count of incoming references.
• Go to definition (F12 / Ctrl+click) from an rdf:resource line to the matching rdf:about block.
• Find all references (Shift+F12) on an object.

Settings

The bars need the glyph margin. If nothing appears: "editor.glyphMargin": true (the default).

Commands: CIM/RDF Lens: Toggle bars, CIM/RDF Lens: Recolour.

Development

node --test "test/*.test.js"                              # 15 tests, no dependencies
node scripts/preview.js leistungsschalter.example.rdf

preview.js draws the same bars with ANSI colours into the terminal -- for a quick look without starting an extension host.

Layout: parser.js (RDF/XML -> definitions + references with positions), graph.js (hierarchy, colour assignment, underline spots), svg.js (the bar image), decorations.js (decoration management), extension.js (wiring). The first three do not know about vscode and are therefore testable without an editor.

Known limits

• VS Code draws one gutter icon per line. Stacked bars therefore have to live in a single SVG; accordingly one decoration type is created per occurring bar sequence (not per line).
• The parser reads attributes, not a DOM. rdf:nodeID, nested anonymous nodes and relationships via rdf:parseType="Collection" are not captured -- for CIM instance graphs, which use rdf:about/rdf:resource throughout, that is enough.
• Relationships across file boundaries are not resolved; a reference to an object in another file stays colourless.