# Step 1 Complete: Oxigraph Setup ✅

## Summary

Successfully set up Oxigraph triplestore in-memory mode with sample data and created SPARQL HTTP client.

## Completed Tasks

### 1.1 Oxigraph Installation ✅
- [x] Downloaded Oxigraph v0.5.2 binary
- [x] Installed to `~/.local/bin/oxigraph_server`
- [x] Created installation script: `scripts/install-oxigraph.sh`

### 1.2 Server Scripts ✅
- [x] `scripts/start-oxigraph-memory.sh` - Start in-memory server (no persistence)
- [x] `scripts/load-sample-data.sh` - Load N-Triples data into default graph
- [x] `scripts/load-and-start.sh` - Combined startup + data loading

**Key Learning**: Use **PUT to `/store?default`** to load data into default graph (not POST)

### 1.3 Sample RDF Data ✅
- [x] Created `data/sample-rdf/dutch-heritage-institutions.nt` (78 triples)
- [x] 6 Dutch heritage institutions:
  - Amsterdam Museum
  - Rijksmuseum
  - Koninklijke Bibliotheek (National Library)
  - Stadsarchief Amsterdam (City Archives)
  - Van Gogh Museum
  - Mauritshuis
- [x] Schema.org vocabulary
- [x] Multilingual labels (English + Dutch)
- [x] Wikidata links via `owl:sameAs`

### 1.4 SPARQL HTTP Client ✅
- [x] Created `src/lib/sparql/client.ts` (200 lines)
  - `SparqlClient` class with methods:
    - `executeSelect()` - SELECT queries
    - `executeAsk()` - ASK queries
    - `executeConstruct()` - CONSTRUCT/DESCRIBE queries
    - `testConnection()` - Health check
    - `getTripleCount()` - Database statistics
  - `SparqlError` exception class
  - Environment configuration via `VITE_SPARQL_ENDPOINT`
  - Timeout support (default 30s)
  - AbortController for cancellation

- [x] Created `tests/unit/sparql-client.test.ts` (20 tests passing, 1 skipped)
  - Constructor tests (4)
  - `executeSelect` tests (5)
  - `executeAsk` tests (2)
  - `executeConstruct` tests (1)
  - `testConnection` tests (2)
  - `getTripleCount` tests (2)
  - Error handling tests (2)
  - Configuration tests (2)

### 1.5 Environment Configuration ✅
- [x] Created `.env.local`:
  ```
  VITE_SPARQL_ENDPOINT=http://localhost:7878/query
  ```

## Technical Notes

### Oxigraph ARM Issue (Documented)
- Persistent storage crashes on macOS ARM (RocksDB bug)
- **Solution**: Use in-memory mode for development
- Trade-off: Data reloads on restart (~1 second)
- Alternative: Docker container (Linux environment)

### Data Loading Method
```bash
# WRONG (creates named graph)
curl -X POST -H 'Content-Type: application/n-triples' \
  --data-binary '@data.nt' http://localhost:7878/store

# CORRECT (loads into default graph)
curl -X PUT -H 'Content-Type: application/n-triples' \
  --data-binary '@data.nt' http://localhost:7878/store?default
```

### SPARQL Endpoint URLs
- **Query endpoint**: `http://localhost:7878/query` (SELECT, ASK, CONSTRUCT, DESCRIBE)
- **Store endpoint**: `http://localhost:7878/store` (data loading)
- **Health check**: `http://localhost:7878/` (returns 200)

## Test Results

**Before**: 148 tests passing  
**After**: 168 tests passing (+20)  
**Status**: ✅ All passing (1 skipped)

## Files Created/Modified

```
frontend/
├── .env.local                          ✅ Created
├── scripts/
│   ├── install-oxigraph.sh             ✅ Created
│   ├── start-oxigraph-memory.sh        ✅ Created
│   ├── load-sample-data.sh             ✅ Modified (PUT method)
│   └── load-and-start.sh               ✅ Created
├── data/
│   └── sample-rdf/
│       └── dutch-heritage-institutions.nt  ✅ Created (comments removed)
├── src/lib/sparql/
│   └── client.ts                       ✅ Created (200 lines)
├── tests/unit/
│   └── sparql-client.test.ts           ✅ Created (21 tests)
├── OXIGRAPH_STATUS.md                  📝 Reference doc
└── PHASE3_TASK7_PLAN.md                📝 Plan doc
```

## Verification

### Server Status
```bash
$ curl -s http://localhost:7878/ && echo "✅ Server running"
```

### Data Verification
```bash
$ curl -X POST \
  -H 'Content-Type: application/sparql-query' \
  -H 'Accept: application/sparql-results+json' \
  --data 'SELECT (COUNT(*) as ?count) WHERE { ?s ?p ?o }' \
  http://localhost:7878/query | jq '.results.bindings[0].count.value'

# Expected output: "78"
```

### Query Example
```bash
$ curl -X POST \
  -H 'Content-Type: application/sparql-query' \
  -H 'Accept: application/sparql-results+json' \
  --data 'SELECT ?museum ?name WHERE { 
    ?museum a <http://schema.org/Museum> ; 
            <http://schema.org/name> ?name 
  } LIMIT 5' \
  http://localhost:7878/query | jq
```

## Next Steps

✅ **Step 1 Complete** - Oxigraph + SPARQL Client  
⏳ **Step 2 Next** - Results Table Component (2.5 hours)

Continue with:
1. Create `src/components/query/ResultsTable.tsx`
2. Create `src/components/query/ResultsTable.css`
3. Features:
   - Display SPARQL SELECT results in table
   - Column sorting
   - Pagination (100 rows/page)
   - URI rendering (clickable links)
   - Cell type styling (URI, literal, bnode)
4. Tests: `tests/unit/results-table.test.tsx` (~12-15 tests)

---

**Status**: ✅ **COMPLETE**  
**Duration**: ~1.5 hours (as estimated)  
**Test Coverage**: +20 tests (168 total)  
**Lines of Code**: ~400 (client + tests)