apilize-protocol — Python SDK for the Apilize Protocol v1

Author financial-modeling containers that speak the Apilize Protocol v1 over CLI stdio. Subclass Model, override the handlers you need, ship a Docker container — the SDK takes care of the session loop, JSON-Lines framing, error envelopes, and exit codes.

Install

pip install apilize-protocol

Hello, Apilize — a complete model in ~30 lines

# model/handlers.py
from apilize_protocol import Model

class HelloValuation(Model):
    def _compute(self, inputs):
        """Pure calculation shared by handle_run and handle_export."""
        years = inputs["assumptions"]["holding_period_years"]
        annual = sum(u["monthly_rent_eur"] for u in inputs["units"]) * 12
        return {
            "cash_flows": [annual] * years,
            "npv": annual * years,
            "irr": 0.0,
            "terminal_value": 0.0,
        }

    def handle_run(self, msg):
        yield {"type": "progress", "stage": "summing", "percent": 50}
        yield {"type": "result", "data": self._compute(msg["input"])}

    def handle_export(self, msg):
        import json
        from pathlib import Path
        out = Path(msg["outputPath"])
        out.write_text(json.dumps(self._compute(msg["input"])))
        return {
            "format": msg["format"],
            "outputPath": str(out),
            "byteSize": out.stat().st_size,
        }

# model/__main__.py
import sys
from .handlers import HelloValuation

if __name__ == "__main__":
    sys.exit(HelloValuation.main())

Then add a data/spec.yaml, data/ui.yaml, data/i18n/en.yaml, copy the Dockerfile.template from this SDK as Dockerfile, and docker build — that's a conformant Apilize Protocol model.

What you get from Model

The session loop, SIGTERM handling, exit-code semantics, JSON-Lines framing, per-message error wrapping, and validation are handled by Model.serve() (invoked via Model.main()).

Container packaging

Copy Dockerfile.template from this SDK into your model repo as Dockerfile. The template:

• Uses python:3.12-slim as base.
• Sets PYTHONUNBUFFERED=1 — required for the session-mode transport to work correctly. Without this, the orchestrator's readline() deadlocks.
• Installs your pyproject.toml (which declares apilize-protocol as a dep).
• Sets ENTRYPOINT ["python", "-m", "model"].

There is no published base image in v1.x; the template is the contract.

Note on the in-repo example Dockerfiles. The Dockerfiles under examples/dcf-example/ and examples/hello-valuation/ install the SDK from the repository's sdk/python/ source via COPY sdk/python /tmp/sdk rather than from PyPI. This is a repo-local-CI convenience — the SDK isn't published to PyPI yet, and the examples need to build against the in-tree source. External authors should use the template above, which installs from pip install . against their pyproject.toml that declares apilize-protocol as a regular dependency. The in-repo example divergence is internal to this repository's CI.

Conformance

The full conformance suite lives in apilize-protocol/conformance/. Run it against your container:

docker build -t my-model .
DOCKER_IMAGE=my-model pytest conformance/tests/

If all tests pass, your container is a conformant Apilize Protocol v1 model.

Optional: logging

The SDK does not own a logging convention beyond "stderr is empty on clean session" (per the protocol contract). If you want diagnostics in container logs during development:

import logging, sys
logging.basicConfig(stream=sys.stderr, level=logging.INFO)

Note that conformance asserts STDERR is empty on clean session exit — disable logging or redirect to a file before running conformance.

Public API

from apilize_protocol import (
    Model,                      # subclass this to write a model
    Kind,                       # Enum: VALUATION / SOURCE / TRANSFORM
    SpecResponse, UiResponse, I18nResponse,
    ValidateResponse, ValidationError,
    RunProgress, RunResult,
    ExportResponse,
    ProtocolError,
    ApilizeProtocolError,       # base exception
    UnsupportedLocaleError,
    UnsupportedFormatError,
    InputValidationError,
    MissingFieldError,
    DEFAULT_PROTOCOL_RANGE,     # "^1.0"
)

License

MIT. See LICENSE in the repository root.

Versioning

SDK versions track protocol minor versions: 1.1.0 SDK targets protocol 1.1.0. SDK-internal additive changes bump the SDK patch version while keeping the protocol target. Breaking changes require a new protocol major (v2) and a corresponding SDK major.