rosetta-serve — a SPARQL endpoint over the ethical-decision lattice

Serve an oxigraph RDF store as a read-only SPARQL 1.1 endpoint with dereferenceable IRIs, so any standard semantic-web client can query the wintermute lattice over HTTP.

Why it exists

The rest of the rosetta family turns ethical decisions into RDF — PROV-O graphs, SHACL reports, signed credentials — and joins them into an oxigraph store. But a store on disk is reachable only from a CLI in-process, and its IRIs don't dereference. A browser, curl, or a Python SPARQLWrapper client has nothing to point at. rosetta-serve closes that gap: it puts the joined graph behind the W3C SPARQL Protocol and makes each resource IRI resolve to a description. The lattice becomes addressable linked data, not a private file.

It is read-only by construction — not by policy you could forget to set, but because no write path is exposed and SPARQL UPDATE is rejected at the HTTP layer.

Install

git clone https://github.com/j0yen/rosetta-serve.git
cd rosetta-serve
cargo build --release
install -Dm755 target/release/rosetta-serve ~/.local/bin/rosetta-serve

Requires rustc ≥ 1.85.

Quickstart

# Confirm a store opens and see its triple count
rosetta-serve check --store ~/.local/share/lattice/store

# Start the endpoint (binds 127.0.0.1:7180 by default)
rosetta-serve up --store ~/.local/share/lattice/store

# Load extra Turtle at startup — e.g. a rosetta-prov decision graph
rosetta-serve up --store ~/.local/share/lattice/store --load decision.ttl

Then query it like any SPARQL endpoint:

# ASK
curl 'http://127.0.0.1:7180/sparql?query=ASK%20{%20?s%20?p%20?o%20}'
# → {"head":{},"boolean":true}

# SELECT with explicit Accept
curl -H 'Accept: application/sparql-results+json' \
  --data-urlencode 'query=SELECT * WHERE { ?s ?p ?o } LIMIT 5' \
  http://127.0.0.1:7180/sparql

# Dereference a resource IRI
curl -H 'Accept: text/turtle' http://127.0.0.1:7180/wo/Dignity

Surfaces

• GET|POST /sparql?query=… — SPARQL 1.1 Protocol. SELECT and ASK return application/sparql-results+json; CONSTRUCT and DESCRIBE content-negotiate Turtle or JSON-LD. SPARQL UPDATE and PUT/DELETE/PATCH are answered 405 Method Not Allowed, and the store is unchanged.
• GET /{prefix}/{local} — IRI dereferencing. Returns a bounded description of the resource, content-negotiated (Turtle / JSON-LD); an unknown IRI returns 404.

A per-query timeout (--timeout, default 30s) aborts a runaway query rather than hanging the server; later requests still succeed.

up flags

Flag	Default	Meaning
--store <dir>	~/.local/share/lattice/store	oxigraph store to serve
--load <ttl>	(none; repeatable)	extra Turtle files merged at startup
--bind <addr>	127.0.0.1:7180	TCP bind address
--timeout <dur>	30s	per-query timeout (500ms, 30s)
--base-iri <iri>	http://wintermute.local	base IRI for dereferencing

Scope

A local-only, read-only query surface — that's the whole job. Out of scope, by design: writes / SPARQL UPDATE, public-internet hosting, OWL/RDFS inference (the store already carries materialized entailments), and authentication / TLS (local-only). JSON-LD output is the simple @graph form, not full framing.

Where it fits

Part of the rosetta family — portable, standards-based exports of ousia-guard's ethical decisions:

• rosetta-prov — a verdict → a W3C PROV-O provenance graph (Turtle / JSON-LD)
• rosetta-shacl — the four guard rules → W3C SHACL shapes + a sh:ValidationReport validator
• rosetta-credential — a verdict → a signed W3C Verifiable Credential
• rosetta-serve (this) — the joined RDF lattice → dereferenceable IRIs and a SPARQL endpoint

rosetta-prov and rosetta-shacl produce the RDF; rosetta-serve is how anything else reaches it.

Status

v0.1, local use. Built on axum 0.8 and oxigraph 0.4. The eight acceptance tests (tests/acceptance_ac*.rs) cover store loading, ASK/SELECT/CONSTRUCT, IRI dereferencing, UPDATE rejection, loading a decision graph, and the query timeout.

License

MIT OR Apache-2.0 at your option. Copyright (c) 2026 Joe Yen.