pydase/docs/user-guide/Tasks.md

Understanding Tasks

In pydase, a task is defined as an asynchronous function without arguments contained in a class that inherits from pydase.DataService. These tasks usually contain a while loop and are designed to carry out periodic functions.

For example, a task might be used to periodically read sensor data, update a database, or perform any other recurring job. One core feature of pydase is its ability to automatically generate start and stop functions for these tasks. This allows you to control task execution via both the frontend and python clients, giving you flexible and powerful control over your service's operation.

Another powerful feature of pydase is its ability to automatically start tasks upon initialization of the service. By specifying the tasks and their arguments in the _autostart_tasks dictionary in your service class's __init__ method, pydase will automatically start these tasks when the server is started. Here's an example:

import pydase


class SensorService(pydase.DataService):
    def __init__(self):
        super().__init__()
        self.readout_frequency = 1.0
        self._autostart_tasks["read_sensor_data"] = ()

    def _process_data(self, data: ...) -> None:
        ...

    def _read_from_sensor(self) -> Any:
        ...

    async def read_sensor_data(self):
        while True:
            data = self._read_from_sensor()
            self._process_data(data)  # Process the data as needed
            await asyncio.sleep(self.readout_frequency)


if __name__ == "__main__":
    service = SensorService()
    pydase.Server(service=service).run()

In this example, read_sensor_data is a task that continuously reads data from a sensor. By adding it to the _autostart_tasks dictionary, it will automatically start running when pydase.Server(service).run() is executed. As with all tasks, pydase will generate start_read_sensor_data and stop_read_sensor_data methods, which can be called to manually start and stop the data reading task. The readout frequency can be updated using the readout_frequency attribute.