Python Client

The Python client package contains generated MXAccess Gateway protobuf bindings, the async mxgateway package, and the mxgw-py test CLI. The package uses the shared proto inputs documented in ../../docs/client-proto-generation.md so gateway and client contracts stay in sync.

Layout

clients/python/
  pyproject.toml
  generate-proto.ps1
  src/mxgateway/
  src/mxgateway/generated/
  src/mxgateway_cli/
  tests/

src/mxgateway/generated contains code produced by grpc_tools.protoc. Do not edit generated files by hand.

Regenerating Protobuf Bindings

Run generation after the shared .proto files or the Python output path changes:

./generate-proto.ps1

The script uses the Python tool path recorded in ../../docs/toolchain-links.md.

Build And Test

Run the Python checks from clients/python:

python -m pip install -e ".[dev]"
python -m pytest
python -m pip wheel . --no-deps --wheel-dir "$env:TEMP\mxgateway-python-wheel"

The tests import the generated gateway and worker stubs, run fake async gateway stubs, verify API key metadata, exercise stream cancellation, load shared value and command fixtures, and check deterministic CLI output.

Library Usage

The library is async-first:

from mxgateway import GatewayClient

async with await GatewayClient.connect(
    endpoint="localhost:5000",
    api_key="mxgw_example",
    plaintext=True,
) as client:
    session = await client.open_session(client_session_name="python-client")
    try:
        server_handle = await session.register("python-client")
        item_handle = await session.add_item(server_handle, "Object.Attribute")
        await session.advise(server_handle, item_handle)
    finally:
        await session.close()

GatewayClient.open_session_raw, GatewayClient.invoke_raw, and GatewayClient.stream_events_raw keep the generated protobuf replies and events available for parity tests. Session helpers call the method-specific MXAccess commands and preserve raw replies on typed command exceptions.

Canceling a Python task cancels the client-side gRPC call or stream wait. It does not abort an in-flight MXAccess COM call inside the worker process.

Authentication And TLS

ClientOptions.api_key adds this metadata to unary calls and streams:

authorization: Bearer <api-key>

The client supports plaintext channels for local development, TLS with system roots, TLS with a custom ca_file, and an optional test server name override. API keys are redacted from option repr output and CLI error output.

CLI

The CLI emits deterministic JSON for automation:

mxgw-py version --json
mxgw-py open-session --endpoint localhost:5000 --plaintext --json
mxgw-py register --session-id <id> --client-name python-client --json
mxgw-py add-item --session-id <id> --server-handle 1 --item Object.Attribute --json
mxgw-py advise --session-id <id> --server-handle 1 --item-handle 2 --json
mxgw-py stream-events --session-id <id> --max-events 1 --json
mxgw-py write --session-id <id> --server-handle 1 --item-handle 2 --type int32 --value 123 --json

Use --api-key or --api-key-env MXGATEWAY_API_KEY to attach API key metadata. smoke opens a session, registers, adds an item, advises, streams a bounded event count, and closes the session in a finally block.

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