uns-kit 0.0.44

Lightweight Python UNS MQTT client (pub/sub + infra topics)

uns-kit (Python)

Lightweight UNS MQTT client for Python. Provides:

• Topic builder compatible with UNS infra topics (uns-infra/<package>/<version>/<process>/).
• Async publish/subscribe via MQTT (using aiomqtt).
• Process + instance status topics (active/heap/uptime/alive + stats).
• Minimal UNS packet builder/parser (data/table) aligned with TS core.

Install (editable)

cd packages/uns-py
poetry install

CLI

After poetry install, an uns-kit-py command is available (renamed to avoid clashing with the Node CLI):

poetry run uns-kit-py publish --host localhost:1883 --topic raw/data/ --value 1
poetry run uns-kit-py subscribe --host localhost:1883 --topic 'uns-infra/#'

Feature-specific dependencies are exposed as optional extras:

pip install "uns-kit[api]"
pip install "uns-kit[cron]"
pip install "uns-kit[api,cron]"

Runtime feature APIs mirror the TypeScript surface:

• await process.create_api_proxy(...)
• await process.create_cron_proxy(...)
• TS-style aliases are also available: createApiProxy(...), createCrontabProxy(...)

Quick start

import asyncio
from pathlib import Path
from uns_kit import ConfigFile, UnsPacket, UnsProcessParameters, UnsProxyProcess

async def main():
    config = ConfigFile.load_config(Path("config.json"))
    infra = config["infra"]
    uns = config["uns"]
    process = UnsProxyProcess(
        infra["host"],
        UnsProcessParameters(process_name=uns.get("processName", "uns-process")),
    )
    await process.start()
    mqtt = await process.create_mqtt_proxy("py")

    # Subscribe
    async with mqtt.client.messages("uns-infra/#") as messages:
        await mqtt.publish_packet("raw/data/", UnsPacket.data(value=1, uom="count"))
        msg = await messages.__anext__()
        print(msg.topic, msg.payload.decode())

    await mqtt.close()
    await process.stop()

asyncio.run(main())

Recommended publishing pattern

If your service publishes UNS topics, prefer:

• UnsProxyProcess
• await process.create_mqtt_proxy(...)
• await proxy.publish_mqtt_message(...)

That is the default application pattern for generated Python services and the path that also maintains the retained .../topics registry used for discovery. Direct UnsMqttClient publishing is lower-level and should not be the default service pattern unless you have a specific reason.

Validity / Liveliness

UNS attributes can declare how the controller decides whether they are live or stale. These fields are optional and default to "interval" with the controller default (~120s) if omitted.

• validityMode: "interval" | "lifecycle" | "static"
• expectedIntervalMs: required for "interval" mode (controller marks stale after ~2x this interval)
• lifecycleEndValue: required for "lifecycle" mode (end-state marker, e.g. "EXITED")

await proxy.publish_mqtt_message({
    "topic": "raw/data/",
    "asset": "line-1",
    "objectType": "motor",
    "objectId": "main",
    "attributes": {
        "attribute": "status",
        "data": {"time": "2025-01-01T00:00:00Z", "value": "RUNNING"},
        "validityMode": "lifecycle",
        "lifecycleEndValue": "STOPPED",
    },
})

Datahub client (last value)

UnsClient provides a minimal REST client for the UNS Datahub API, including the batch last-value endpoint.

from uns_kit import UnsClient

client = UnsClient("https://datahub.example.com", api_base_path="/api")
client.login("[e-mail]", "password")

values = client.last_value([
    "raw/data/line-1/motor/main/temperature",
    "raw/data/line-1/motor/main/status",
])
print(values)

Config placeholders (env + Infisical)

uns-py now resolves config placeholders in the same style as uns-core. For Infisical placeholders, install the optional extra:

pip install "uns-kit[infisical]"

Example config.json:

{
  "uns": {
    "graphql": "https://example/graphql",
    "rest": "https://example/rest",
    "email": "[e-mail]",
    "password": { "provider": "env", "key": "UNS_PASSWORD" },
    "processName": "my-process"
  },
  "infra": {
    "host": "mqtt.example.local",
    "port": 1883,
    "username": "mqtt-user",
    "password": {
      "provider": "infisical",
      "path": "/mqtt",
      "key": "password",
      "environment": "dev"
    }
  }
}

Load resolved config with cache semantics:

from uns_kit import ConfigFile, SecretResolverOptions, InfisicalResolverOptions

resolved = ConfigFile.load_config(
    "config.json",
    SecretResolverOptions(
        infisical=InfisicalResolverOptions(
            environment="dev",
            project_id="your-project-id"
        )
    )
)

Resilient subscriber

async for msg in client.resilient_messages("uns-infra/#"):
    print(msg.topic, msg.payload.decode())

Examples

• examples/publish.py — publish 5 data packets.
• examples/subscribe.py — resilient subscription with auto-reconnect.
• examples/load_test.py — interactive publish burst.

Create a new project

uns-kit-py create my-uns-py-app
cd my-uns-py-app
poetry install
poetry run python main.py

To add optional feature scaffolding later:

poetry run uns-kit-py configure-api .
poetry run uns-kit-py configure-cron .

Create a new project from a service bundle

uns-kit-py create --bundle ./service.bundle.json
uns-kit-py create --bundle ./service.bundle.json --dest ./my-dir
uns-kit-py create --bundle ./service.bundle.json --dest . --allow-existing

Bundle-driven create uses service.bundle.json as the source of truth. The Python CLI:

• scaffolds the base Python app from the existing default template
• copies the original bundle into the project root as service.bundle.json
• generates SERVICE_SPEC.md and AGENTS.md
• applies supported bundle features such as vscode and devops

When --bundle is used, the default destination is ./<metadata.name>. The Python CLI only accepts bundles with scaffold.stack = "python" and currently supports scaffold.template = "default" for this MVP. If the bundle targets TypeScript instead, use uns-kit create --bundle ....

Create a sandbox app in this repo

From the monorepo root:

pnpm run py:sandbox

This creates sandbox-app-py/ using the default Python template. When created inside this monorepo, pyproject.toml is automatically set to use local editable uns-kit: uns-kit = { path = "../packages/uns-py", develop = true }.

Notes

• Default QoS is 0.
• Instance status topics are published every 10 seconds; stats every 60 seconds.
• Packet shape mirrors the TypeScript core: {"version":"1.3.0","message":{"data":{...}},"sequenceId":0}.
• Windows: the library sets WindowsSelectorEventLoopPolicy() to avoid add_reader/add_writer NotImplementedError.

TODO (parity with TS core)

• Handover manager parity: subscribe to wildcard active and handover topics, keep new instances passive until timeout or handover completion, and support handover_intent, handover_request, handover_subscriber, handover_fin, and handover_ack.
• Publish throttling / queue parity: add buffered ordered publishing instead of direct proxy-path publish, plus publisher/subscriber active-passive controls and passive-drain behavior.
• Status parity: add process-level alive and uptime, publisher/subscriber active flags everywhere, published/subscribed message count and byte metrics, and process identity on active status packets.
• API endpoints registry: mirror @uns-kit/api produced endpoints when Python gets an API surface, and use full UNS identity for endpoint keys and paths: topic + asset + objectType + objectId + attribute.
• Optional: dictionary/measurement helpers + CLI wrapper.