Metadata-Version: 2.1
Name: swim-protocol
Version: 0.3.6
Summary: SWIM protocol implementation for exchanging cluster membership status and metadata.
Home-page: https://github.com/icgood/swim-protocol/
Author: Ian Good
Author-email: ian@icgood.net
License: MIT
Description: swim-protocol
        =============
        
        [SWIM protocol][0] implementation for exchanging cluster membership status and
        metadata.
        
        [![build](https://github.com/icgood/swim-protocol/actions/workflows/python-package.yml/badge.svg)](https://github.com/icgood/swim-protocol/actions/workflows/python-package.yml)
        [![Coverage Status](https://coveralls.io/repos/github/icgood/swim-protocol/badge.svg?branch=main)](https://coveralls.io/github/icgood/swim-protocol?branch=main)
        [![PyPI](https://img.shields.io/pypi/v/swim-protocol.svg)](https://pypi.python.org/pypi/swim-protocol)
        [![PyPI](https://img.shields.io/pypi/pyversions/swim-protocol.svg)](https://pypi.python.org/pypi/swim-protocol)
        [![PyPI](https://img.shields.io/pypi/l/swim-protocol.svg)](https://pypi.python.org/pypi/swim-protocol)
        
        This library is intended to fit into an [asyncio][1] event loop to help
        synchronize a distributed group of processes.
        
        #### [Introduction](https://icgood.github.io/swim-protocol/intro.html)
        
        #### [API Documentation](https://icgood.github.io/swim-protocol/)
        
        ## Install and Usage
        
        ```console
        $ pip install swim-protocol
        ```
        
        #### Running the Demo
        
        There is a [demo][2] application included as a reference implementation. Try it
        out by running the following, each from a new terminal window, and use _Ctrl-C_
        to exit:
        
        ```console
        $ swim-protocol-demo -c --name 127.0.0.1:2001 --peer 127.0.0.1:2003 --metadata name one
        $ swim-protocol-demo -c --name 127.0.0.1:2002 --peer 127.0.0.1:2001 --metadata name two
        $ swim-protocol-demo -c --name 127.0.0.1:2003 --peer 127.0.0.1:2001 --metadata name three
        $ swim-protocol-demo -c --name 127.0.0.1:2004 --peer 127.0.0.1:2003 --metadata name four
        ```
        
        Every 10 seconds or so, each member will randomize its `token` metadata field,
        which should be disseminated across the cluster with [eventual consistency][6].
        
        ### Getting Started
        
        First you should create a new [UdpConfig][100] object:
        
        ```python
        from swimprotocol.udp import UdpConfig
        
        config = UdpConfig(local_name='127.0.0.1:2001',
                           local_metadata={'name': b'one'},
                           peers=['127.0.0.1:2002'])
        ```
        
        All other config arguments have default values, which are tuned somewhat
        arbitrarily with a small cluster of 3-4 members in mind.
        
        Now you can create the cluster members manager and transport layer, and enter
        the event loop:
        
        ```python
        from contextlib import AsyncExitStack
        from swimprotocol.members import Members
        from swimprotocol.udp import UdpTransport
        
        transport = UdpTransport(config)
        members = Members(config)
        async with AsyncExitStack() as stack:
            worker = await stack.enter_async_context(transport.enter(members))
            await worker.run()  # or schedule as a task
        ```
        
        These snippets demonstrate the UDP transport layer directly. For a more generic
        approach that uses [argparse][11] and [load_transport][12], check out the
        [demo][2].
        
        If your application is deployed as a [Docker Service][13], the [UdpConfig][100]
        `discovery=True` keyword argument can be used to discover configuration based
        on the service name. See the [documentation][14] for more comprehensive usage.
        
        ### Checking Members
        
        The [Members][101] object provides a few ways to check on the cluster and its
        members:
        
        ```python
        for member in members.non_local:
            # all other known cluster members
            print(member.name, member.status, member.metadata)
        
        from swimprotocol.status import Status
        for member in members.get_status(Status.AVAILABLE):
            # all cluster members except offline
            print(member.name, member.status, member.metadata)
        ```
        
        Alternatively, listen for status or metadata changes on all members:
        
        ```python
        from swimprotocol.member import Member
        
        async def _updated(member: Member) -> None:
            print('updated:', member.name, member.status, member.metadata)
        
        async with AsyncExitStack() as stack:
            # ...
            stack.enter_context(members.listener.on_notify(_updated))
        ```
        
        ### UDP Transport Security
        
        The [UdpTransport][102] transport layer (the only included transport
        implementation) uses salted [hmac][7] digests to sign each UDP packet payload.
        Any UDP packets received that are malformed or have an invalid signature are
        *silently* ignored. The eventual consistency model should recover from packet
        loss.
        
        The signatures rely on a [shared secret][8] between all cluster members, given
        as the `secret=b'...'` argument to the [Config][100] constructor. If
        `secret=None` is used, it defaults to [`uuid.getnode()`][9] but this is **not
        secure** for production setups unless all sockets are bound to a local loopback
        interface.
        
        The cluster member metadata is **not** encrypted during transmission, so only
        private networks should be used if metadata includes any secret data, or that
        secret data should be encrypted separately by the application. Also be aware
        that low [MTU][10] sizes on public networks may affect the ability to
        synchronize larger amounts of metadata.
        
        ## Development
        
        First off, I suggest activating a [venv][3]. Then, install the development
        requirements and a local link to the *swim-protocol* package:
        
        ```
        $ pip install -r requirements-dev.txt
        ```
        
        ### Type Hinting
        
        This project makes heavy use of Python's [type hinting][4] system, with the
        intention of a clean run of [mypy][5]:
        
        ```console
        $ mypy
        ```
        
        No code contribution will be accepted unless it makes every effort to use type
        hinting to the extent possible and common in the rest of the codebase.
        
        [0]: https://www.cs.cornell.edu/projects/Quicksilver/public_pdfs/SWIM.pdf
        [1]: https://docs.python.org/3/library/asyncio.html
        [2]: https://github.com/icgood/swim-protocol/blob/main/swimprotocol/demo/__init__.py
        [3]: https://docs.python.org/3/library/venv.html
        [4]: https://docs.python.org/3/library/typing.html
        [5]: http://mypy-lang.org/
        [6]: https://en.wikipedia.org/wiki/Eventual_consistency
        [7]: https://docs.python.org/3/library/hmac.html
        [8]: https://en.wikipedia.org/wiki/Shared_secret
        [9]: https://docs.python.org/3/library/uuid.html#uuid.getnode
        [10]: https://en.wikipedia.org/wiki/Maximum_transmission_unit
        [11]: https://docs.python.org/3/library/argparse.html
        [12]: https://icgood.github.io/swim-protocol/swimprotocol.html#swimprotocol.transport.load_transport
        [13]: https://docs.docker.com/engine/swarm/how-swarm-mode-works/services/
        [14]: https://icgood.github.io/swim-protocol/swimprotocol.udp.html#docker-services
        
        [100]: https://icgood.github.io/swim-protocol/swimprotocol.udp.html#swimprotocol.udp.UdpConfig
        [101]: https://icgood.github.io/swim-protocol/swimprotocol.html#swimprotocol.members.Member
        [102]: https://icgood.github.io/swim-protocol/swimprotocol.udp.html#swimprotocol.udp.UdpTransport
        ## MIT License
        
        Copyright (c) 2021 Ian Good
        
        Permission is hereby granted, free of charge, to any person obtaining a copy
        of this software and associated documentation files (the "Software"), to deal
        in the Software without restriction, including without limitation the rights
        to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
        copies of the Software, and to permit persons to whom the Software is
        furnished to do so, subject to the following conditions:
        
        The above copyright notice and this permission notice shall be included in all
        copies or substantial portions of the Software.
        
        THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
        IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
        FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
        AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
        LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
        OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
        SOFTWARE.
        
Platform: UNKNOWN
Classifier: Development Status :: 3 - Alpha
Classifier: Intended Audience :: Developers
Classifier: Intended Audience :: Information Technology
Classifier: License :: OSI Approved :: MIT License
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 3.9
Requires-Python: ~=3.9
Description-Content-Type: text/markdown
