messageflux 0.1.0

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MessageFlux

This package is used to create long-running services, that read messages from devices, and handles them. The devices in this package are meant to be composable - meaning that added functionality can come from wrapping devices in other devices.

Requirements

Python 3.7+

Installation

$ pip install messageflux

Extra Requirements (Example)

$ pip install messageflux[rabbitmq]

Example

Create it

• Create a file main.py with:

from messageflux import MessageHandlingService, MessageHandlerBase, InputDevice, ReadResult
from messageflux.iodevices.in_memory_device import InMemoryDeviceManager


class MyMessageHandler(MessageHandlerBase):
    def handle_message(self, input_device: InputDevice, read_result: ReadResult):
        message = read_result.message
        print(f'message bytes: {message.bytes}')  # Do somthing with the message...


input_device_manager = InMemoryDeviceManager()
# write messages to devices here...

my_example_service = MessageHandlingService(message_handler=MyMessageHandler(),
                                            input_device_manager=input_device_manager,
                                            input_device_names=['MY_QUEUE'])
if __name__ == '__main__':
    my_example_service.start()  # this blocks indefinitely (until CTRL-C or sigterm)

Run it

python main.py 

Using Multi Processing for concurrency

from messageflux import MessageHandlingService, MessageHandlerBase, InputDevice, ReadResult
from messageflux.multiprocessing import get_service_runner, ServiceFactory


class MyMessageHandler(MessageHandlerBase):
    def handle_message(self, input_device: InputDevice, read_result: ReadResult):
        message = read_result.message
        print(f'message bytes: {message.bytes}')  # Do somthing with the message...


class MyServiceFactory(ServiceFactory):

    def create_service(self) -> MessageHandlingService:
        """
        we import the devices in 'create_service' so that all the imports will be in the child process.
        this is only a precaution, but recommended
        """
        from messageflux.iodevices.in_memory_device import InMemoryDeviceManager

        input_device_manager = InMemoryDeviceManager()
        # write messages to devices here...

        my_example_service = MessageHandlingService(message_handler=MyMessageHandler(),
                                                    input_device_manager=input_device_manager,
                                                    input_device_names=['MY_QUEUE'])
        return my_example_service


if __name__ == '__main__':  # you must do this in multiprocess running
    service_to_run = get_service_runner(service_factory=MyServiceFactory(),
                                        instance_count=5)  # this will run 5 child processes

    service_to_run.start()  # this starts the child processes and blocks indefinitely (until CTRL-C or sigterm)

Optional Requirements

• messageflux[rabbitmq] - for using the rabbitmq device
• messageflux[objectstorage] - for using the s3 device wrappers
• messageflux[dev] - for running tests and developing for this package
• messageflux[all] - all extras required for all devices