Python Client API¶

The PyPI package includes a generic Python client for controlling a running lab-link server over the same WebSocket protocol used by browser frontends. It is useful for scripts or Python packages that need to drive a GUI-backed instrument service without adding app-specific REST endpoints.

Async Client¶

AsyncLabLinkClient is the primary implementation.

from lab_link import AsyncLabLinkClient, SyncCommandError

async with AsyncLabLinkClient("ws://127.0.0.1:8000/sync/ws") as sync:
    snapshot = sync.snapshot()
    try:
        ack = await sync.send_command(
            "set_voltage",
            {"channel": 0, "value": 1.2},
        )
    except SyncCommandError as exc:
        print(exc.code, exc.message)

connect() waits for the initial snapshot message before returning. Incoming patch messages update the cached snapshot with JSON Patch, including patches that arrive before the matching command acknowledgement.

Sync Client¶

LabLinkClient wraps the async client with a background event loop for scripts.

from lab_link import LabLinkClient

with LabLinkClient("ws://127.0.0.1:8000/sync/ws") as sync:
    print(sync.snapshot())
    ack = sync.send_command("set_voltage", {"channel": 0, "value": 1.2})

Events¶

Snapshots are returned as deep copies so callers cannot mutate the client cache. Subscribe to patches or command errors when a script needs to react to live updates.

unsubscribe = sync.on_patch(lambda event: print(event.version, event.patch))

send_command() returns CommandAck on success and raises SyncCommandError for structured server-side command failures or client-side timeouts.