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Structured Data Format

Git Revolution for Source Code​

Git transformed software development by providing structured, versioned data management for source code:

Before Git​

  • Source code scattered across developer machines
  • Manual file sharing through email and shared directories
  • No systematic way to track changes or merge contributions
  • Difficult collaboration between distributed teams
  • Complex branching and merging processes

Git's Innovation​

  • Structured Storage: Content-addressable storage with SHA-1 hashing
  • Distributed Architecture: Complete history available in every repository
  • Deterministic Operations: Same operations produce identical results
  • Efficient Merging: Three-way merge algorithms for conflict resolution
  • Cryptographic Integrity: Hash-based verification of data integrity

Impact on Software Development​

  • Enabled distributed development at massive scale
  • Standardized collaboration workflows (pull requests, code review)
  • Created foundation for modern CI/CD systems
  • Enabled reproducible builds and deployments
  • Universal adoption across the software industry

TRF: Git for Traceability Data​

TRF applies the same structured data principles to traceability evidence:

Current State: Traceability Chaos​

  • Evidence scattered across dozens of specialized tools
  • Manual aggregation for compliance assessments
  • Inconsistent data formats between organizations
  • No systematic way to track evidence evolution
  • Difficult validation of evidence completeness and integrity

TRF's Structured Approach​

  • TWPack Format: ZIP archives with structured JSONL data
  • Content Addressing: Deterministic artifact identification
  • Cryptographic Verification: SHA-256 hashing and digital signatures
  • Version Control Integration: Git-compatible evidence packages
  • Schema Validation: JSON schemas ensure data consistency

TWPack: Structured Evidence Archives​

Archive Structure​

example.twpack (ZIP archive)
├── manifest.json              # Package metadata and verification
├── provenance.json           # Creation metadata and integrity
├── artifacts.jsonl           # Core artifact definitions
├── links.jsonl              # Traceability relationships
├── signatures.json          # Cryptographic signatures (optional)
└── attachments/             # Binary files and documents
    ├── requirements.pdf
    ├── test-results.xml
    └── model-weights.bin

JSONL Data Format​

Each line contains a complete JSON object for one artifact:

{"id": "req:REQ-001", "type": "requirement", "title": "System shall detect obstacles", "content": "The autonomous driving system shall detect obstacles within 100m with 99.9% accuracy", "created": "2024-01-15T10:30:00Z", "hash": "sha256:a1b2c3..."}
{"id": "test:TC-001", "type": "test", "title": "Obstacle detection test", "status": "passed", "coverage": {"requirements": ["req:REQ-001"]}, "created": "2024-01-20T14:45:00Z", "hash": "sha256:d4e5f6..."}
{"id": "model:OD-v2.1", "type": "model", "title": "Obstacle detection neural network", "framework": "pytorch", "accuracy": 0.999, "training_data": "dataset:KITTI-2024", "created": "2024-01-18T09:15:00Z", "hash": "sha256:g7h8i9..."}

Deterministic Packaging​

  • Artifacts sorted by identifier for consistent ordering
  • Timestamps normalized to UTC with standardized precision
  • Binary attachments included with content hashes
  • Metadata fields follow strict schema validation
  • Same input data produces identical TWPack files

Version Control Integration​

Git Compatibility​

TWPack files integrate seamlessly with git workflows:

# Add evidence package to repository
git add evidence/sprint-1.twpack
git commit -m "Add sprint 1 traceability evidence"

# Track evidence evolution across branches
git log --oneline evidence/
git diff HEAD~1 evidence/sprint-1.twpack

# Merge evidence from multiple teams
git merge feature/ai-model-evidence

Binary Diff Support​

  • Git LFS integration for large TWPack files
  • Structured diff tools for JSONL content comparison
  • Merge conflict resolution for traceability data
  • Branch-based evidence development workflows

Evidence Provenance​

# Track evidence authorship and timeline
git log --follow evidence/safety-case.twpack

# Verify evidence integrity across commits
tw verify evidence/safety-case.twpack --commit abc123

# Audit evidence modifications
git blame evidence/requirements.twpack

Data Consistency and Validation​

Schema-Based Validation​

JSON schemas ensure consistent data structure:

{
  "$schema": "https://trf-spec.org/schemas/v2/artifact.json",
  "type": "object",
  "required": ["id", "type", "title", "created", "hash"],
  "properties": {
    "id": {"type": "string", "pattern": "^[a-z]+:[A-Z0-9_-]+$"},
    "type": {"enum": ["requirement", "test", "design", "component"]},
    "hash": {"type": "string", "pattern": "^sha256:[a-f0-9]{64}$"}
  }
}

Automated Validation​

# Validate TWPack structure and schemas
tw validate evidence.twpack

# Check artifact relationships
tw check-links evidence.twpack

# Verify cryptographic signatures
tw verify-signatures evidence.twpack

Cross-Package Consistency​

  • Universal artifact identifiers enable cross-package references
  • Dependency validation ensures referenced artifacts exist
  • Version compatibility checking for schema evolution
  • Automated detection of circular dependencies

Cryptographic Integrity​

Content Verification​

  • SHA-256 hashing for every artifact and attachment
  • Merkle tree structure for efficient partial verification
  • Digital signatures for package authenticity
  • Timestamp verification for evidence chronology

Trust Chain​

{
  "signatures": [
    {
      "signer": "org:automotive-supplier",
      "algorithm": "RSA-SHA256",
      "signature": "base64-encoded-signature",
      "certificate": "X.509-certificate",
      "timestamp": "2024-01-20T15:30:00Z"
    }
  ]
}

Multi-Party Verification​

  • Multiple signatures for multi-organizational evidence
  • Counter-signatures for evidence review and approval
  • Witness signatures for audit trail completeness
  • Revocation checking for compromised certificates

Querying and Analysis​

Structured Queries​

TWPack's structured format enables sophisticated analysis:

# Find all requirements without test coverage
tw query evidence.twpack --kind requirement --filter "not covered_by test"

# Trace model lineage from requirements to deployment
tw trace evidence.twpack --from "req:REQ-001" --to "deployment:*"

# Generate coverage matrix
tw coverage evidence.twpack --matrix requirements tests

Cross-Package Analysis​

# Analyze evidence across multiple packages
tw query *.twpack --aggregate --kind model --field accuracy

# Find gaps in multi-tier supply chain evidence
tw gap-analysis tier1.twpack tier2.twpack tier3.twpack

# Validate end-to-end traceability
tw trace-chain customer-requirements.twpack system-design.twpack implementation.twpack

Integration with Analytics Tools​

  • Export to Pandas DataFrames for data science analysis
  • Integration with Jupyter notebooks for evidence exploration
  • GraphQL APIs for web-based evidence browsers
  • SQL exports for enterprise data warehouse integration

Scalability and Performance​

Efficient Storage​

  • Compressed ZIP format reduces storage requirements
  • Incremental packaging for large evidence collections
  • Deduplication of common artifacts across packages
  • Streaming processing for large TWPack files

Parallel Processing​

  • JSONL format enables line-by-line parallel processing
  • Map-reduce compatible for distributed analysis
  • Incremental validation for fast feedback cycles
  • Caching mechanisms for repeated queries

This structured approach to traceability data provides the foundation for systematic evidence management, automated compliance validation, and scalable cross-organizational collaboration.