aiomas 2.0.1

Asyncio-based, layered networking library providing request-reply channels, RPC, and multi-agent systems.

aiomas – A library for multi-agent systems and RPC based on asyncio

aiomas is an easy-to-use library for request-reply channels, remote procedure calls (RPC) and multi-agent systems (MAS). It’s written in pure Python on top of asyncio.

Here are three simple examples that show the different layers of aiomas and what they add on top of each other:

The request-reply channel has the lowest level of abstraction (but already offers more then vanilla asyncio):

>>> import aiomas
>>>
>>>
>>> async def handle_client(channel):
...     """Handle a client connection."""
...     req = await channel.recv()
...     print(req.content)
...     await req.reply('cya')
...     await channel.close()
>>>
>>>
>>> async def client():
...     """Client coroutine: Send a greeting to the server and wait for a
...     reply."""
...     channel = await aiomas.channel.open_connection(('localhost', 5555))
...     rep = await channel.send('ohai')
...     print(rep)
...     await channel.close()
>>>
>>>
>>> server = aiomas.run(aiomas.channel.start_server(('localhost', 5555), handle_client))
>>> aiomas.run(client())
ohai
cya
>>> server.close()
>>> aiomas.run(server.wait_closed())

The RPC layer adds remote procedure calls on top of it:

>>> import aiomas
>>>
>>>
>>> class MathServer:
...     router = aiomas.rpc.Service()
...
...     @router.expose
...     def add(self, a, b):
...         return a + b
...
>>>
>>> async def client():
...     """Client coroutine: Call the server's "add()" method."""
...     rpc_con = await aiomas.rpc.open_connection(('localhost', 5555))
...     rep = await rpc_con.remote.add(3, 4)
...     print('What’s 3 + 4?', rep)
...     await rpc_con.close()
>>>
>>> server = aiomas.run(aiomas.rpc.start_server(('localhost', 5555), MathServer()))
>>> aiomas.run(client())
What’s 3 + 4? 7
>>> server.close()
>>> aiomas.run(server.wait_closed())

Finally, the agent layer hides some of the boilerplate code required to setup the sockets and allows agent instances to easily talk with each other:

>>> import aiomas
>>>
>>> class TestAgent(aiomas.Agent):
...     def __init__(self, container):
...         super().__init__(container)
...         print('Ohai, I am %s' % self)
...
...     async def run(self, addr):
...         remote_agent = await self.container.connect(addr)
...         ret = await remote_agent.service(42)
...         print('%s got %s from %s' % (self, ret, remote_agent))
...
...     @aiomas.expose
...     def service(self, value):
...         return value
>>>
>>> c = aiomas.Container.create(('localhost', 5555))
>>> agents = [TestAgent(c) for i in range(2)]
Ohai, I am TestAgent('tcp://localhost:5555/0')
Ohai, I am TestAgent('tcp://localhost:5555/1')
>>> aiomas.run(until=agents[0].run(agents[1].addr))
TestAgent('tcp://localhost:5555/0') got 42 from TestAgentProxy('tcp://localhost:5555/1')
>>> c.shutdown()

aiomas is released under the MIT license. It requires Python 3.4 and above and runs on Linux, OS X, and Windows.

Installation

aiomas requires Python >= 3.6 (or PyPy3 >= 5.10.0). It uses the JSON codec by default and only has pure Python dependencies.

Install aiomas via pip by running:

$ pip install aiomas

You can enable the optional MsgPack codec or its Blosc compressed version by installing the corresponding features (note, that you need a C compiler to install them):

$ pip install aiomas[mp]   # Enables the MsgPack codec
$ pip install aiomas[mpb]  # Enables the MsgPack and MsgPackBlosc codecs

Features

aiomas just puts three layers of abstraction around raw TCP / unix domain sockets provided by asyncio:

Agents and agent containers:

The top-layer provides a simple base class for your own agents. All agents live in a container.

Containers take care of creating agent instances and performing the communication between them.

The container provides a clock for the agents. This clock can either be synchronized with the real (wall-clock) time or be set by an external process (e.g., other simulators).

RPC:

The rpc layer implements remote procedure calls which let you call methods on remote objects nearly as if they were normal objects:

Instead of ret = obj.meth(arg) you write ret = await obj.meth(arg).

Request-reply channel:

The channel layer is the basis for the rpc layer. It sends JSON or MsgPack encoded byte strings over TCP or unix domain sockets. It also maps replies (of success or failure) to their corresponding request.

Other features:

• TLS support for authorization and encrypted communication.

• Interchangeable and extensible codecs: JSON and MsgPack (the latter optionally compressed with Blosc) are built-in. You can add custom codecs or write (de)serializers for your own objects to extend a codec.

• Deterministic, emulated sockets: A LocalQueue transport lets you send and receive message in a deterministic and reproducible order within a single process. This helps testing and debugging distributed algorithms.

Planned features

Some ideas for future releases:

• Optional automatic re-connect after connection loss

Contribute

• Issue Tracker: https://gitlab.com/sscherfke/aiomas/issues

• Source Code: https://gitlab.com/sscherfke/aiomas

Set-up a development environment with:

$ virtualenv -p `which python3` aiomas
$ pip install -r requirements-setup.txt

Run the tests with:

$ pytest
$ # or
$ tox

Support

• Documentation: https://aiomas.readthedocs.io/en/latest/

• Mailing list: https://groups.google.com/forum/#!forum/python-tulip

• Stack Overflow: http://stackoverflow.com/questions/tagged/aiomas

• IRC: #asyncio

License

The project is licensed under the MIT license.

Changelog

2.0.1 – 2017-12-29

• [CHANGE] Restore support for Python 3.5 so that the docs on Read the Docs build again.

2.0.0 – 2017-12-28

• [BREAKING] Converted to f-Strings and async/await syntax. The minimum required Python versions are now Python 3.6 and PyPy3 5.10.0.

• [BREAKING] Removed aiomas.util.async() and aiomas.util.create_task().

• [CHANGE] Move from Bitbucket and Mercurial to GitLab and Git.

• [FIX] Adjust to asyncio changes and explicitly pass references to the current event loop where necessary.

You can find information about older versions in the documentation.

Authors

The original author of aiomas is Stefan Scherfke.

The initial development has kindly been supported by OFFIS.