# Ontology Syntax Validate

> Provides a script and instructions to validate RDF syntax of every file in a repository using rapper (raptor2) with rdflib fallback. Covers Turtle, RDF/XML, N-Triples, JSON-LD, and more. Use before any other ontology check — if files don't parse, nothing else works.

- Skill: `daniel-dona/ontology-syntax-validate` (Agent Skill, multi-file: 4 files)
- Install (CLI): `npx skillmds@latest add daniel-dona/ontology-syntax-validate`
- Raw SKILL.md: https://api.skillmd.com/api/skills/daniel-dona/ontology-syntax-validate/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- License: MIT
- Author: daniel-dona (https://skillmd.com/u/daniel-dona)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/daniel-dona/ontology-syntax-validate

---


# Ontology Syntax Validation

Validates that every RDF file in a repository is syntactically valid. Uses
**rapper** from [raptor2](https://librdf.org/raptor/) (the reference RDF parser
from the W3C ecosystem) as primary validator. Falls back to **rdflib** if
rapper is not installed.

**Single script:** `scripts/syntax_validate.py`

## Supported Formats

| Extension | Format | Parser |
|-----------|--------|--------|
| `.ttl` | Turtle | rapper / rdflib |
| `.owl` | RDF/XML | rapper / rdflib |
| `.rdf` | RDF/XML | rapper / rdflib |
| `.nt` | N-Triples | rapper / rdflib |
| `.nq` | N-Quads | rapper |
| `.trig` | TriG | rapper / rdflib |
| `.jsonld` | JSON-LD | rdflib (rapper fallback) |
| `.html`, `.xhtml` | RDFa | rapper |

## Setup

Rapper is a system tool — install once:

```bash
sudo apt install raptor2-utils    # Debian/Ubuntu
brew install raptor               # macOS
```

For the rdflib fallback (if rapper is unavailable), use a venv:

```bash
python3 -m venv .venv
source .venv/bin/activate
pip install rdflib
```
> **After finishing:** deactivate the venv and remove it (`deactivate && rm -rf .venv`).
> Skip this if the user asks to keep the environment.

If you only use rapper, skip the venv setup — rapper is a system tool.

## Usage

```bash
python scripts/syntax_validate.py . -o SYNTAX_REPORT.md

# Force rdflib even if rapper is installed
python scripts/syntax_validate.py . --rdflib

# JSON output
python scripts/syntax_validate.py . --format json
```

## Standardized Report

All skills support `--format report` which outputs a common JSON schema:
```json
{
  "skill": "skill-name",
  "summary": {"errors": N, "warnings": N, "info": N},
  "issues": [{"file": ".ttl", "element": ":Class", "message": "...",
              "severity": "error|warning|info", "check": "RULE",
              "suggestion": "fix"}]
}
```
This format is consumed by `ontology-full-audit` to produce unified reports.


## Output Files

**Never write files into the repository without permission.** Before generating
any report or output file, ask the user where to save it (e.g. `-o ../report.md`
or an absolute path outside the repo). The default output path in script
examples is only a suggestion — always confirm with the user first.

## Important Rules

1. **Syntax validation is the first gate.** If a file doesn't parse, no other
   skill (typo, SKOS, OOPS, SHACL) can process it. Run this first.

2. **rapper is stricter than rdflib.** It may flag valid-but-ambiguous
   constructs as warnings. Treat rapper errors as authoritative.

3. **rapper is stricter than rdflib.** It may flag valid-but-ambiguous
   constructs. The script automatically falls back to rdflib per file when
   rapper fails — check the report for `⚠️ rapper failed, parsed with rdflib`
   notes to identify format mismatches.