semantica/docs/reference/change_management.md

Change Management

Enterprise-grade version control and audit trails for knowledge graphs and ontologies with data integrity verification

Overview

The Semantica change management module provides enterprise-grade version control, audit trails, and compliance tracking for knowledge graphs and ontologies. Designed for high-stakes domains where every change must be tracked, verified, and auditable with complete data integrity guarantees.

• :material-history:{ .lg .middle } Version Control

  ---

  Complete snapshot management with SHA-256 integrity verification

• :material-database:{ .lg .middle } Dual Storage

  ---

  InMemory (development) and SQLite (production) with ACID guarantees

• :material-graph:{ .lg .middle } Knowledge Graph Versioning

  ---

  Entity and relationship-level change tracking with detailed diffs

• :material-shape:{ .lg .middle } Ontology Versioning

  ---

  Structural change tracking for classes, properties, and axioms

• :material-clipboard-check:{ .lg .middle } Audit Trail Compliance

  ---

  Complete change logs with author attribution and timestamps

• :material-shield-check:{ .lg .middle } Data Integrity

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  SHA-256 checksums for tamper detection and verification

• :material-compare:{ .lg .middle } Change Comparison

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  Detailed diff algorithms for entities, relationships, and ontology structures

• :material-backup-restore:{ .lg .middle } Backward Compatibility

  ---

  Legacy support for existing ontology version management

• Enterprise Version Control — Complete snapshot management with SHA-256 integrity verification
• Dual Storage Backends — InMemory (development) and SQLite (production) with ACID guarantees
• Knowledge Graph Versioning — Entity and relationship-level change tracking with detailed diffs
• Ontology Versioning — Structural change tracking for classes, properties, and axioms
• Audit Trail Compliance — Complete change logs with author attribution and timestamps
• Data Integrity — SHA-256 checksums for tamper detection and verification
• Change Comparison — Detailed diff algorithms for entities, relationships, and ontology structures
• Backward Compatibility — Legacy support for existing ontology version management

---

Quick Start

from semantica.change_management import TemporalVersionManager

# Initialize version manager
manager = TemporalVersionManager(storage_path="versions.db")

# Create versioned snapshot
snapshot = manager.create_snapshot(
    graph={"entities": [...], "relationships": [...]},
    version_label="v1.0",
    author="user@example.com",
    description="Initial knowledge graph"
)

# Compare versions
diff = manager.compare_versions("v1.0", "v2.0")

What this does:

• Initializes version manager with persistent SQLite storage
• Creates a versioned snapshot of knowledge graph data
• Compares two versions to detect changes
• Provides complete audit trail with author attribution

---

Core Components

ChangeLogEntry

Standardized metadata for tracking version changes with validation.

from semantica.change_management import ChangeLogEntry

@dataclass
class ChangeLogEntry:
    timestamp: str          # ISO 8601 format
    author: str             # Email address
    description: str        # Max 500 characters
    change_id: Optional[str] = None

Key Method:

• create_now(author, description, change_id=None) - Create entry with current timestamp

Storage Backends

InMemoryVersionStorage — Fast, volatile storage for development and testing.

from semantica.change_management import InMemoryVersionStorage

storage = InMemoryVersionStorage()

SQLiteVersionStorage — Persistent storage with ACID guarantees for production.

from semantica.change_management import SQLiteVersionStorage

storage = SQLiteVersionStorage("versions.db")

VersionStorage (Abstract) — Base interface for custom storage implementations.

Core Methods:

• save(snapshot) - Store version snapshot
• get(label) - Retrieve by version label
• list_all() - List all versions
• exists(label) - Check if version exists
• delete(label) - Remove version

---

Version Managers

BaseVersionManager

Abstract base class providing common version management functionality.

from semantica.change_management import BaseVersionManager

manager = BaseVersionManager(storage_path="versions.db")

Common Methods:

• list_versions() - Get all version metadata
• get_version(label) - Retrieve specific version
• verify_checksum(snapshot) - Validate data integrity

TemporalVersionManager

Knowledge Graph Version Management

Perfect for tracking changes in knowledge graphs with entity and relationship diffs.

from semantica.change_management import TemporalVersionManager

manager = TemporalVersionManager(storage_path="kg_versions.db")

# Create snapshot
snapshot = manager.create_snapshot(
    graph={
        "entities": [
            {"id": "e1", "name": "Entity 1", "type": "Person"},
            {"id": "e2", "name": "Entity 2", "type": "Organization"}
        ],
        "relationships": [
            {"source": "e1", "target": "e2", "type": "works_for"}
        ]
    },
    version_label="v1.0",
    author="user@example.com",
    description="Initial knowledge graph"
)

# Compare versions with detailed diffs
diff = manager.compare_versions("v1.0", "v2.0")
print(f"Entities added: {diff['summary']['entities_added']}")
print(f"Relationships modified: {diff['summary']['relationships_modified']}")

Key Features:

• Entity-level change tracking
• Relationship diff analysis
• SHA-256 checksums for integrity
• Detailed change summaries

OntologyVersionManager

Ontology Version Management

Designed for structural changes in ontologies with class, property, and axiom tracking.

from semantica.change_management import OntologyVersionManager

manager = OntologyVersionManager(storage_path="ontology_versions.db")

# Create ontology snapshot
snapshot = manager.create_snapshot(
    ontology={
        "uri": "https://example.com/ontology",
        "structure": {
            "classes": ["Person", "Organization"],
            "properties": ["name", "email"],
            "axioms": ["Person hasEmail exactly 1 Email"]
        }
    },
    version_label="ont_v1.0",
    author="architect@example.com",
    description="Initial ontology design"
)

# Compare structural changes
diff = manager.compare_versions("ont_v1.0", "ont_v2.0")
print(f"Classes added: {diff['classes_added']}")
print(f"Axioms modified: {diff['axioms_modified']}")

Key Features:

• Class and property tracking
• Axiom change detection
• Structural comparison
• Import/export support

---

Incremental / Delta processing

For large-scale knowledge graphs, reprocessing the entire dataset on every update is computationally expensive. Semantica supports Delta-Aware Pipelines, allowing you to compute the exact differences (added and removed triples) between the two graph snapshots and run validation, enrichment, or export jobs only on the changes.

Delta Pipeline Example

from semantica.change_management import TemporalVersionManager
from semantica.pipeline import PipelineBuilder, ExecutionEngine

# a. Initialize your managers
version_manager = TemporalVersionManager(store_graph="kg_version.db")
triplet_store = get_my_triplet_store()

# b. Build a delta-aware pipeline
builder = PipelineBuilder()
builder.add_step(
    step_name="validate_changes",
    step_type="validation",
    handler=my_validation_handler,
    delta_mode=True, # Enables incremental processing
    base_version_id="v1.0",
    target_version_id="v1.1",
)

pipeline = builder.build("incremental_nightly_job")

# c. Execute the pipeline
engine = ExecutionEngine()

# The engine dynamically intercepts the flow, computes the delta on the
# database backend, and passes ONLY the changed triples to the handler.
result = engine.execute_pipeline(
    pipeline,
    data={}, # Is ignored in delta mode
    version_manager=version_manager,
    triplet_store=triplet_store
)

---

Data Integrity

compute_checksum

Generate SHA-256 checksum for data integrity verification.

from semantica.change_management import compute_checksum

data = {"entities": [...], "relationships": [...]}
checksum = compute_checksum(data)
print(f"SHA-256: {checksum}")

Use cases:

• Verify data integrity before storing snapshots
• Detect unauthorized modifications to version data
• Ensure consistency across distributed systems
• Generate unique identifiers for data versions

verify_checksum

Validate data integrity using stored checksums.

from semantica.change_management import verify_checksum

snapshot = manager.get_version("v1.0")
is_valid = verify_checksum(snapshot)

if not is_valid:
    print("WARNING: Data integrity compromised!")

Use cases:

• Validate snapshot integrity after retrieval
• Detect data corruption or tampering
• Ensure compliance with data integrity requirements
• Verify backup and restore operations

---

Legacy Support

VersionManager

Original ontology version manager for backward compatibility.

from semantica.change_management import VersionManager, OntologyVersion

Note: Use OntologyVersionManager for new projects.

---

Error Handling

from semantica.utils.exceptions import ValidationError, ProcessingError

try:
    snapshot = manager.create_snapshot(...)
except ValidationError as e:
    print(f"Invalid input: {e}")
except ProcessingError as e:
    print(f"Operation failed: {e}")

Common Errors:

• ValidationError - Invalid email, missing fields, bad timestamps
• ProcessingError - Database issues, file system errors

---

Best Practices

Performance Tips

• Use InMemoryVersionStorage for development/testing
• Use SQLiteVersionStorage for production
• Implement retention policies for old versions

Security Considerations

• Validate author emails for audit trails
• Use checksums for data integrity
• Store sensitive data with appropriate permissions

Usage Patterns

from semantica.change_management import TemporalVersionManager

# Development workflow
dev_manager = TemporalVersionManager()  # In-memory

# Production workflow  
prod_manager = TemporalVersionManager(
    storage_path="secure/production_versions.db"
)

# Audit trail generation
for version in prod_manager.list_versions():
    print(f"{version['timestamp']}: {version['description']} by {version['author']}")

---

Ontology Diff & Migration

Semantica allows you to treat ontology schema changes with the same rigor as database migrations. By comparing two versions, you can generate a machine-readable diff and a structured impact report to catch breaking changes before they reach production.

Comparing Versions

The OntologyEngine provides a high-level API to orchestrate the comparison of two schema versions.

from semantica.ontology.engine import OntologyEngine

engine = OntologyEngine()

# Generate a migration impact report between v1.0 and v2.0
report = engine.compare_versions(
    base_id="v1.0",
    target_id="v2.0"
)

print(f"Total changes detected: {report['summary']['total_changes']}")

---

Report Format

The compare_versions method returns a dictionary with a machine-readable diff and a human-readable impact analysis:

{
  "summary": {
    "total_changes": 12
  },
  "impact_classification": {
    "breaking": [
      {
        "entity_uri": "http://example.org/Person",
        "severity": "critical",
        "description": "Class Person removed.",
        "mitigation": "Migrate orphaned instances."
      }
    ],
    "potentially_breaking": [],
    "safe": []
  },
  "recommendations": [
    "[BREAKING] Schedule downtime or validate existing data."
  ],
  "diff": {
    "added_classes": [],
    "removed_classes": [],
    "changed_classes": [],
    "added_properties": [],
    "removed_properties": [],
    "changed_properties": []
  },
  "validation_results": {
    "valid": true,
    "consistent": true,
    "satisfiable": true,
    "errors": [],
    "warnings": []
  },
  "graph_validation": {
    "valid": false,
    "errors": ["Instance data violates new domain constraint"],
    "warnings": []
  }
}