python-alpaca-server

This is an easy to use Python server for ASCOM Alpaca. It can be run on any system that running Python 3.12 or higher, including a Raspberry Pi. This allows you to easily create new ASCOM Alpaca devices.

Nothing complicated here, just create a new class that implements your logic and inherits from one of the base device classes.

Then start up a new AlpacaServer. The server automatically enables discovery as well.

Example

pip install python-alpaca-server

Edit app.py

from typing import List

from python_alpaca_server.app import AlpacaServer, Description
from python_alpaca_server.devices.safetymonitor import SafetyMonitor
from python_alpaca_server.errors import NotImplementedError
from python_alpaca_server.request import ActionRequest, CommandRequest, CommonRequest, PutConnectedRequest

# Inherit from the base SafetyMonitor class, and implement the methods.
class MySafetyMonitor(SafetyMonitor):
    def __init__(self, unique_id: str):
        super().__init__(unique_id)
        self._connected = False

    def put_action(self, req: ActionRequest) -> str:
        raise NotImplementedError(req)

    def put_command_blind(self, req: CommandRequest) -> None:
        raise NotImplementedError(req)

    def put_command_bool(self, req: CommandRequest) -> bool:
        raise NotImplementedError(req)

    def put_command_string(self, req: CommandRequest) -> str:
        raise NotImplementedError(req)

    def get_connected(self, req: CommonRequest) -> bool:
        return self._connected

    def put_connected(self, req: PutConnectedRequest) -> None:
        self._connected = req.Connected

    def get_description(self, req: CommonRequest) -> str:
        return "My Description"

    def get_driverinfo(self, req: CommonRequest) -> str:
        return "My Driver Info"

    def get_driverversion(self, req: CommonRequest) -> str:
        return "0.1.0"

    def get_interfaceversion(self, req: CommonRequest) -> int:
        return 1

    def get_name(self, req: CommonRequest) -> str:
        return "MySafetyMonitor"

    def get_supportedactions(self, req: CommonRequest) -> List[str]:
        return []

    def get_issafe(self, req: CommonRequest) -> bool:
        if not self._connected:
            return False

        # TODO: Check something to see if we are safe to observe. Return True if safe.
        return False


def get_server_description() -> Description:
    return Description(
        ServerName="MyServer",
        Manufacturer="MyManufacturer",
        ManufacturerVersion="0.1.0",
        Location="MyLocation",
    )


if __name__ == "__main__":
    import uvicorn

    port = 8000

    # Choose a unique ID to pass into MySafetyMonitor. This ID should stay the same
    # across server restarts.
    svr = AlpacaServer(get_server_description, [MySafetyMonitor("other")])

    # Create a FastAPI application we can attach to uvicorn or any other WSGI server.
    app = svr.create_app(port)

    try:
        uvicorn.run(app, host="0.0.0.0", port=port)
    except KeyboardInterrupt:
        pass

Run

python app.py

ASCOM Alpaca Reference

• ASCOM Master Interface Documentation - Official API specifications for all device types
• Local OpenAPI specs in docs/:
  • AlpacaDeviceAPI_v1.yaml - Device API (camera, telescope, focuser, etc.)
  • AlpacaManagementAPI_v1.yaml - Management API (discovery, configuration)