DTCS — Data Transformation Contract Standard

Vendor-neutral specification and reference implementation for expressing the semantics of data transformations.

Status: Draft
Specification version: 1.0.0-draft
Reference implementation: 0.2.0 (Phase 0.2 — Contract Model)
Document dtcsVersion: 1.0.0 (accepted by the reference validator for compatible 1.0.x releases)

See ROADMAP.md for milestone status and CHANGELOG.md for release notes.

Overview

SPEC.md is the authoritative normative specification for DTCS. It defines transformation contracts, the canonical object model, validation, diagnostics, conformance, and governance — without prescribing execution engines, storage, or orchestration.

This repository contains:

Install

Published packages (after tagging v0.2.0):

cargo install dtcs --version 0.2.0
pip install dtcs==0.2.0

Both installs provide a dtcs CLI on PATH (validate, inspect, diagnostics, version).

The current PyPI/crates.io release is 0.1.2 until v0.2.0 is tagged. See CONTRIBUTING.md for the release workflow.

Quick start

Read the specification

less SPEC.md

Build the Rust crate

cargo build
cargo test
cargo run -- validate examples/customer_normalize.dtcs.yaml
cargo run -- inspect examples/customer_normalize.dtcs.yaml

Use the Python package

pip install maturin
maturin develop --features python
python -m dtcs validate examples/customer_normalize.dtcs.yaml
python -m dtcs inspect examples/customer_normalize.dtcs.yaml
pytest python/tests -v

import dtcs

report = dtcs.parse_and_validate(open("examples/customer_normalize.dtcs.yaml", "rb").read())
assert dtcs.is_valid(report)

The reference implementation through Phase 0.2 implements:

DTCS Document → Parser → Canonical Object Model → Validator → Diagnostics

Phase 0.2 adds metadata validation, extended type system checks (conversions, collections, extension types), expression typing, and I/O interface depth (optional inputs, streaming, pre/postconditions).

Execution, backend compilation, and runtime behavior remain out of scope. See docs/implementation/non-goals.md.

Repository layout

dtcs/
├── SPEC.md                 # Normative specification (source of truth)
├── Cargo.toml              # Rust crate manifest
├── pyproject.toml          # Python package manifest (maturin)
├── Cargo.lock              # Pinned dependencies (binary crate)
├── CHANGELOG.md            # Release notes
├── README.md
├── CONTRIBUTING.md
├── LICENSE
├── .github/workflows/      # CI
├── docs/
│   ├── README.md           # Documentation index
│   ├── editorial/          # Specification authoring process
│   └── implementation/     # Reference implementation guides
├── examples/               # Example transformation contracts
├── python/                 # Python package source
├── src/                    # Rust library, CLI binary, validation
├── tests/                  # Integration tests and fixtures
└── .cursor/prompts/        # Cursor build prompt

Contributing

See CONTRIBUTING.md for editorial conventions, implementation guidelines, and the review process.

When implementation guidance conflicts with the specification, SPEC.md wins. See docs/implementation/spec-usage.md.

License

Licensed under the Apache License, Version 2.0. See LICENSE.