HTTP API

OWLGraph exposes its API over HTTP on port 8080 (configurable). All endpoints accept and return JSON unless otherwise noted.

Ontology Endpoints

POST /ontology

Load an OWL ontology in Turtle format.

curl -X POST http://localhost:8080/ontology \
  -H "Content-Type: text/turtle" \
  --data-binary @your-ontology.ttl

Response:

{
  "classes": 11,
  "objectProperties": 5,
  "dataProperties": 4,
  "compiledSchema": "type Animal { ... }",
  "status": "success",
  "message": "Ontology loaded and materializer activated"
}

What happens:

Parses Turtle into OWL internal representation
Validates OWL2 RL profile compliance
Compiles classes to Dgraph types and properties to predicates
Applies compiled schema to the database
Persists ontology for restart recovery
Initializes reasoning engine and introspection
Triggers retroactive materialization for existing data

POST /ontology?validate=true

Validate an ontology without applying it:

curl -X POST "http://localhost:8080/ontology?validate=true" \
  -H "Content-Type: text/turtle" \
  --data-binary @your-ontology.ttl

Returns the compiled schema and class counts without side effects.

GET /ontology/introspect

List all classes in the loaded ontology:

curl http://localhost:8080/ontology/introspect

GET /ontology/introspect?class=ClassName

Get details for a specific class:

curl "http://localhost:8080/ontology/introspect?class=Dog"

{
  "iri": "Dog",
  "superClasses": ["Mammal", "Animal"],
  "subClasses": ["GoldenRetriever", "Labrador"],
  "disjointWith": ["Cat"],
  "properties": [
    {
      "iri": "hasOwner",
      "type": "ObjectProperty",
      "domain": ["Animal"],
      "range": ["Person"],
      "isFunctional": true
    }
  ]
}

GET /ontology/introspect?subclasses=ClassName

Get subclasses of a class:

# Direct subclasses only
curl "http://localhost:8080/ontology/introspect?subclasses=Animal"

# All descendants (transitive)
curl "http://localhost:8080/ontology/introspect?subclasses=Animal&transitive=true"

GET /ontology/introspect?superclasses=ClassName

Get superclasses:

curl "http://localhost:8080/ontology/introspect?superclasses=GoldenRetriever&transitive=true"

Query Endpoints

POST /query

Execute a DQL query:

curl -X POST http://localhost:8080/query \
  -H "Content-Type: application/dql" \
  -d '{ q(func: type(Animal)) { name dgraph.type } }'

Response:

{
  "data": {
    "q": [
      { "name": "Fido", "dgraph.type": ["Dog", "Mammal", "Animal"] }
    ]
  },
  "extensions": {
    "server_latency": { "parsing_ns": 1234, "processing_ns": 5678 }
  }
}

Mutation Endpoints

POST /mutate

Execute a mutation:

# JSON mutation with immediate commit
curl -X POST "http://localhost:8080/mutate?commitNow=true" \
  -H "Content-Type: application/json" \
  -d '{
    "set": [{ "dgraph.type": "Dog", "name": "Rex" }]
  }'

Query parameters:

commitNow=true — commit immediately (no transaction)

Response:

{
  "data": {
    "uids": { "blank-0": "0x1" }
  },
  "extensions": {
    "server_latency": { "parsing_ns": 1234, "processing_ns": 5678 }
  }
}

Schema Endpoints

POST /alter

Apply a schema change directly (bypasses ontology system):

curl -X POST http://localhost:8080/alter \
  -d 'name: string @index(term) .'

Caution: Prefer loading ontologies via /ontology instead of raw /alter. The ontology endpoint handles schema compilation, materialization setup, and persistence automatically.

Health Endpoint

GET /health

curl http://localhost:8080/health

Returns cluster health status.

GraphQL Endpoint

POST /graphql

Execute a GraphQL query against the auto-generated schema:

curl -X POST http://localhost:8080/graphql \
  -H "Content-Type: application/json" \
  -d '{ "query": "{ queryDog { name hasOwner { name } } }" }'