Class Diagram to Neo4j Extraction Skill

Overview

This skill extracts structured data from UML class diagrams (images) and populates Neo4j graph databases. It's designed for:

•TMF (TM Forum) API specification diagrams
•UML class diagrams
•Entity-relationship diagrams
•Schema diagrams

Workflow

1. Image Analysis

•Use vision models (GPT-4 Vision, Claude Vision, etc.) to analyze diagram images
•Extract text, boxes, lines, and relationships
•Identify entities, properties, and relationships

2. Structured Extraction

•Parse entities (classes) with their properties
•Extract relationships (associations, inheritance, etc.)
•Capture cardinality and relationship metadata
•Handle color coding and visual indicators

3. Data Normalization

•Convert to structured format (YAML/JSON)
•Normalize entity names and types
•Standardize relationship types
•Handle references and aliases

4. Neo4j Population

•Generate Cypher queries
•Create nodes with properties
•Create relationships with metadata
•Handle constraints and indexes

Usage Patterns

Pattern 1: Direct Image → Neo4j

python

from classdiagram_to_neo4j import extract_and_populate

# Extract from image and populate Neo4j
extract_and_populate(
    image_path="diagrams/product_offering.png",
    neo4j_uri="bolt://localhost:7687",
    neo4j_user="neo4j",
    neo4j_password="password"
)

Pattern 2: Extract → Review → Populate

python

from classdiagram_to_neo4j import extract_diagram, populate_neo4j

# Step 1: Extract to JSON/YAML
data = extract_diagram(
    image_path="diagrams/product_offering.png",
    output_format="json",
    output_path="extracted.json"
)

# Step 2: Review/edit JSON if needed
# ... manual review ...

# Step 3: Populate Neo4j
populate_neo4j(
    data=data,
    neo4j_uri="bolt://localhost:7687",
    neo4j_user="neo4j",
    neo4j_password="password"
)

Pattern 3: Batch Processing

python

from classdiagram_to_neo4j import extract_diagram, populate_neo4j

# Process multiple diagrams
diagrams = [
    "diagrams/product_offering.png",
    "diagrams/category.png",
    "diagrams/pricing.png"
]

for diagram_path in diagrams:
    data = extract_diagram(diagram_path, output_format="json")
    populate_neo4j(
        data=data,
        neo4j_uri="bolt://localhost:7687",
        neo4j_user="neo4j",
        neo4j_password="password"
    )

Diagram Types Supported

TMF-Style Diagrams

•ProductOffering hub diagrams
•Category relationships
•Specification diagrams
•Reference entity diagrams

UML Class Diagrams

•Classes with attributes
•Associations with multiplicities
•Inheritance hierarchies
•Aggregations and compositions

Schema Diagrams

•Database schemas
•API schemas
•Domain models

Extraction Process

Step 1: Vision Analysis

The vision model analyzes the image and extracts:

•Entities: Boxes/classes with names
•Properties: Attributes within entities
•Relationships: Lines/arrows between entities
•Metadata: Cardinality, roles, types
•Visual Indicators: Colors, borders, dashed lines

Step 2: Structured Output

Extracted data is normalized into:

yaml

meta:
  source: "diagrams/product_offering.png"
  extracted_at: "2024-01-01T00:00:00Z"
  diagram_type: "uml_class"

entities:
  ProductOffering:
    label: "ProductOffering"
    properties:
      - name: "id"
        type: "string"
        required: true
      - name: "name"
        type: "string"
        required: true
      - name: "isBundle"
        type: "boolean"
        required: false

relationships:
  - from: "ProductOffering"
    to: "ProductSpecification"
    type: "has_specification"
    cardinality: "0..1"
    direction: "out"
    properties:
      role: null

Step 3: Neo4j Population

Generates Cypher queries:

cypher

// Create schema block
MERGE (sb:SchemaBlock {id: 'tmf620_productoffering'})
SET sb.title = 'ProductOffering Diagram',
    sb.artifact = 'diagrams/productoffering.png';

// Create entities with FQN
MERGE (e:Entity {fqn: 'tmf620_productoffering#ProductOffering'})
SET e.name = 'ProductOffering',
    e.specId = 'tmf620_productoffering',
    e.kind = 'Entity';

// Create fields
MERGE (f:Field {fqn: 'tmf620_productoffering#ProductOffering.name'})
SET f.name = 'name',
    f.type = 'string',
    f.required = true;

// Link field to entity
MATCH (e:Entity {fqn: 'tmf620_productoffering#ProductOffering'})
MATCH (f:Field {fqn: 'tmf620_productoffering#ProductOffering.name'})
MERGE (e)-[:HAS_FIELD]->(f);

// Create relationships
MATCH (from:Entity {fqn: 'tmf620_productoffering#ProductOffering'})
MATCH (to:Entity {fqn: 'tmf620_productoffering#ProductSpecification'})
MERGE (from)-[r:RELATES_TO {
    type: 'has_specification',
    fromCardinality: '0..1',
    toCardinality: '1',
    direction: 'out'
}]->(to);

Key Features

1. Scalable Data Model

•Uses stable labels (:Entity, :RefType, :SchemaBlock) instead of per-class labels
•Uses FQN (Fully Qualified Name) for entity identity: <specId>#<entityName>
•Uses generic RELATES_TO relationship type with type property
•Avoids label explosion and supports namespacing
•See references/SCALABLE_RELATIONSHIP_MODEL.md

2. Provenance Tracking

•Tracks source diagram via SchemaBlock nodes
•Uses FQN for entity identity (supports multiple versions)
•Maintains extraction metadata (specId, extracted_at)
•Links entities to schema blocks via CONTAINS_ENTITY

3. Conflict Resolution

•Handles duplicate entities
•Merges properties intelligently
•Resolves relationship conflicts

4. Validation

•Validates extracted data structure before population
•Checks for missing required fields
•Verifies relationship consistency
•Validates cardinality formats
•Can be disabled with --no-validate flag

5. Property Persistence

•Properties are stored as :Field nodes
•Fields linked to entities via HAS_FIELD relationships
•Property metadata (type, required, default) fully persisted

Configuration

Vision Model Settings

yaml

vision:
  provider: "openai"  # or "anthropic"
  model: "gpt-4o"  # or "claude-3-5-sonnet-20241022"
  max_tokens: 8000
  temperature: 0.1
  use_structured_output: true  # Uses JSON mode when available

Neo4j Settings

yaml

neo4j:
  uri: "bolt://localhost:7687"
  user: "neo4j"
  password: "password"
  database: "neo4j"
  create_constraints: true
  create_indexes: true

Extraction Settings

yaml

extraction:
  include_properties: true
  include_methods: false
  normalize_names: true
  handle_references: true
  extract_cardinality: true

Output Formats

YAML Format

See schema_examples/tmf620/productoffering_hub.core.example.yaml for example.

JSON Format

json

{
  "meta": {
    "source": "diagrams/product_offering.png",
    "extracted_at": "2024-01-01T00:00:00Z"
  },
  "entities": {
    "ProductOffering": {
      "label": "ProductOffering",
      "properties": [...]
    }
  },
  "relationships": [...]
}

Cypher Format

See schema_examples/neo4j/tmf620_productoffering_scalable_model.cypher for example.

Integration with Existing Tools

With TMF MCP Builder

python

import sys
from pathlib import Path
sys.path.insert(0, str(Path(__file__).parent / "scripts"))

from extract_and_populate import extract_and_populate
from neo4j import GraphDatabase

# Extract and populate
extract_and_populate(
    image_path="diagrams/tmf620_productoffering.png",
    neo4j_password="password"
)

# Query for relevant subgraph
driver = GraphDatabase.driver("bolt://localhost:7687", auth=("neo4j", "password"))
with driver.session() as session:
    result = session.run("""
        MATCH (e:Entity {name: 'ProductOffering'})-[r:RELATES_TO*1..2]->(related)
        WHERE r.type IN ['has_specification', 'has_price']
        RETURN e, r, related
    """)
    # Process results...
driver.close()

Best Practices

•
Pre-process Images
- •Ensure high resolution
- •Remove noise and artifacts
- •Standardize format (PNG preferred)
•
Validate Extraction
- •Review extracted YAML/JSON
- •Verify entity names
- •Check relationship cardinalities
•
Incremental Updates
- •Use merge strategies
- •Track changes
- •Maintain provenance
•
Query Optimization
- •Create indexes on common properties
- •Use relationship type filters
- •Limit hop depth
•
Error Handling
- •Handle missing entities
- •Validate relationships
- •Log extraction issues

Examples

See examples/ directory for:

•Simple UML class diagram extraction
•TMF ProductOffering diagram extraction
•Batch processing example
•Custom extraction rules

References

•references/SCALABLE_RELATIONSHIP_MODEL.md - Relationship modeling approach
•references/VISION_EXTRACTION_PROMPTS.md - Vision model prompts
•NEO4J_REQUIREMENTS.md - Neo4j server version requirements
•schema_examples/neo4j/ - Example Cypher scripts

Neo4j Server Requirements

Important: Relationship property indexes require Neo4j server version 4.3+.

•The requirements.txt specifies the Python driver version, not the server version
•Check your Neo4j server version: neo4j version or CALL dbms.components()
•See NEO4J_REQUIREMENTS.md for full compatibility details

Troubleshooting

Common Issues

•
Low Extraction Quality
- •Increase image resolution
- •Use better vision model
- •Provide more context in prompts
•
Missing Relationships
- •Check diagram clarity
- •Verify relationship detection logic
- •Review extraction output
•
Neo4j Population Errors
- •Check constraints
- •Verify relationship types
- •Review Cypher syntax
•
Performance Issues
- •Batch operations
- •Use transactions
- •Create indexes

Future Enhancements

•Support for sequence diagrams
•Support for activity diagrams
•Multi-page diagram handling
•Automatic relationship inference
•Diagram versioning and diff