communica

Inter-Process Communication (IPC) for Python

Sometimes there is no need for complicated, blazingly fast frameworks with incredible throughput and even more incredible configuration. You just want to make your processes communicate with each other. And that's what this library is for.

Install

pip install communica

You can install additional dependencies for various features

pip install communica[extraname1, extraname2]

Extra name	Feature
orjson	Faster JSON library, which makes available OrjsonSerializer from communica.serializers.json module.
adaptix	Makes available communica.serializers.AdaptixSerializer, which provides request and response data validation.
rabbitmq	Makes available communica.connectors.RmqConnector, to use AMQP server for communication.

Usage

For clarity, the only difference between *Clients and *Servers is who connected to who (Clients connect to Server). Beyond this they are both almost identical. So i will use termins like "requesting side" and "responding side".

First, you should pick an Entity. This will be the primary object for interaction with the library, you can think of it as "Client" or "App" object. Currently, only request-reply based entities are available. For instance, Simple entities (SimpleServer and SimpleClient) enable you to send messages and receive responses (provided the other side defines corresponding handler).

Then, choose how Entities will connect to each other. This is what Connectors for -- they used to establish connections. No matter which technology Connector use, Entities don't know anything about it, so you can swap connectors without rewriting much code. Connectors are serializable to ASCII string, refer to their .dump_state() and .load_state() methods for details, as the method parameters are specific to each connector type.

Finally, data in request should somehow be transformed from Python objects to bytes and back. This is called serialization and that thing is done by Serializers. Currently, there are two serializers: JsonSerializer, which passes objects directly to json.dump and AdaptixSerializer, which first converts objects using adaptix library before JSON serialization. AdaptixSerializer is particularly useful for handling Python objects with complex structures.

Putting it all together

Server:

import asyncio
from communica import SimpleServer, TcpConnector

connector = TcpConnector('localhost', 16161)

def handler(data: str):
    print(f'Received {data!r} from client')
    return f'Thanks for your {data!r}!'

server = SimpleServer(
    connector=connector,
    handler=handler
)

asyncio.run(server.run())

Client:

import asyncio
from communica import SimpleClient, TcpConnector

connector = TcpConnector('localhost', 16161)

async def main():
    async with SimpleClient(connector=connector) as client:
        resp = await client.request('hello')
        print(f'Server responded with {resp!r}')

asyncio.run(main())

As you can see, server was started using Entity.run() and client with Entity's context manager. This methods are available for both Client and Server.
Also there is an example for Route entities.

Entities:
Pairs of Client and Server entities.

Entity	Description
Simple	These entities have only one handler and two operations: request (send message, wait response, return it) and throw (schedule message and don't wait for response). "Throwing" is useful in cases such as logging events or fire-and-forget notifications
Route	Similar to simple, but have multiple handlers, identified by exact string match.

Connectors:
Things which making connections. Connector can be serialized and passed to other processes, e.g. parent process creates connector, run server with it and start childs, which run clients with same connector.

Connector	Description
LocalConnector	Uses Named Pipes on Windows and Unix domain sockets on other systems, if available. This is similar to multiprocessing's connection, but LocalConnector doesn't fallback to TCP (multiprocessing does).
TcpConnector	Uses TCP/IP protocol.
RmqConnector	Uses AMQP message broker, based on aiormq library.