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Triple Store Configuration

OntoCast supports multiple triple store backends for storing and managing RDF data. This guide covers the setup and configuration of supported triple stores.

Overview

OntoCast supports the following triple store backends:

  1. Apache Fuseki (Recommended) - Native RDF triple store with SPARQL support
  2. Neo4j with n10s plugin - Graph database with RDF capabilities
  3. Filesystem - Local file-based storage (fallback)

When multiple triple stores are configured, OntoCast uses the following priority order: 1. Fuseki (if FUSEKI_URI and FUSEKI_AUTH are set) 2. Neo4j (if NEO4J_URI and NEO4J_AUTH are set) 3. Filesystem (default fallback)

Environment Variables

Configure your triple store connection using environment variables in your main .env file:

# Fuseki Configuration (Preferred)
FUSEKI_URI=http://localhost:3032/test
FUSEKI_AUTH=admin/abc123-qwe

# Neo4j Configuration (Alternative)
NEO4J_URI=bolt://localhost:7689
NEO4J_AUTH=neo4j/test!passfortesting

Apache Fuseki Setup

Sample configurations are provided here: ontocast/docker.

1. Prepare the environment file: 

cd docker/fuseki
cp .env.example .env
# Edit with your values

Example docker/fuseki/.env.example: 

IMAGE_VERSION=secoresearch/fuseki:5.1.0
ENVIRONMENT_ACTUAL=test
CONTAINER_NAME="${ENVIRONMENT_ACTUAL}.fuseki"
STORE_FOLDER="$HOME/tmp/${CONTAINER_NAME}"
TS_PORT=3032
TS_PASSWORD="abc123-qwe"
TS_USERNAME="admin"
UID=1000
GID=1000

2. Start/Stop Fuseki: 

# Start
cd docker/fuseki
docker compose --env-file .env fuseki up -d

# Stop
# (use the container name from your .env, e.g. test.fuseki)
docker compose stop test.fuseki

3. Access Fuseki:

Neo4j with n10s Plugin Setup

1. Prepare the environment file: 

cd docker/neo4j
cp .env.example .env
# Edit with your values

Example docker/neo4j/.env.example: 

IMAGE_VERSION=neo4j:5.20
SPEC=test
CONTAINER_NAME="${SPEC}.sem.neo4j"
NEO4J_PORT=7476
NEO4J_BOLT_PORT=7689
STORE_FOLDER="$HOME/tmp/${CONTAINER_NAME}"
NEO4J_PLUGINS='["apoc", "graph-data-science", "n10s"]'
NEO4J_AUTH="neo4j/test!passfortesting"

2. Start/Stop Neo4j: 

# Start
cd docker/neo4j
docker compose --env-file .env neo4j up -d

# Stop
docker compose stop neo4j

3. Access Neo4j:

  • Browser: http://localhost:7476
  • Username: neo4j
  • Password: test!passfortesting
  • Bolt: bolt://localhost:7689

Filesystem Storage (Fallback)

If neither Fuseki nor Neo4j is configured, OntoCast will store ontologies and facts as Turtle files in the working directory.

No setup required.

Triple Store Comparison

Feature Fuseki Neo4j + n10s Filesystem
RDF Native ✅ Yes ⚠️ Via plugin ✅ Yes
SPARQL ✅ Full 1.1 ❌ Limited ❌ No
Setup Complexity ✅ Simple ⚠️ Moderate ✅ Very Simple
Visualization ⚠️ Basic ✅ Excellent ❌ None
Production Ready ✅ Yes ✅ Yes ❌ No

Best Practices

  • Use Filesystem for quick setup and testing.
  • Use Fuseki for RDF-focused or production deployments.
  • Use Neo4j if you need advanced graph analytics or visualization.
  • Monitor triple store performance and logs.
  • Backup your data regularly.

Troubleshooting

Fuseki

# Check if Fuseki is running
curl http://localhost:3032/$/ping

# Restart Fuseki
docker compose restart fuseki

Neo4j

# Check if Neo4j is running
curl http://localhost:7476

# Check n10s plugin
cypher-shell -u neo4j -p test!passfortesting "CALL n10s.graphconfig.show()"

Common Problems

  • Connection Refused: Triple store not running
  • Authentication Failed: Incorrect credentials
  • Dataset Not Found: Dataset not created in Fuseki
  • Plugin Not Loaded: n10s plugin not installed in Neo4j

Clean Triple Store Initialization

You can start OntoCast with the --clean option to initialize the triple store (Neo4j or Fuseki) as clean. This will delete all data from the triple store on startup.

serve --working-directory WORKING_DIR --ontology-directory ONTOLOGY_DIR --clean
  • Warning: This will delete all data from the configured triple store (Neo4j or Fuseki) on startup. Use with caution in production environments!