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Async http client/server framework (asyncio)

Project description

Async http client/server framework

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:width: 64px
:alt: aiohttp logo


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Key Features

- Supports both client and server side of HTTP protocol.
- Supports both client and server Web-Sockets out-of-the-box and avoids
Callback Hell.
- Provides Web-server with middlewares and pluggable routing.

Getting started


To get something from the web:

.. code-block:: python

import aiohttp
import asyncio

async def fetch(session, url):
async with session.get(url) as response:
return await response.text()

async def main():
async with aiohttp.ClientSession() as session:
html = await fetch(session, '')

if __name__ == '__main__':
loop = asyncio.get_event_loop()


An example using a simple server:

.. code-block:: python

# examples/
from aiohttp import web

async def handle(request):
name = request.match_info.get('name', "Anonymous")
text = "Hello, " + name
return web.Response(text=text)

async def wshandle(request):
ws = web.WebSocketResponse()
await ws.prepare(request)

async for msg in ws:
if msg.type == web.WSMsgType.text:
await ws.send_str("Hello, {}".format(
elif msg.type == web.WSMsgType.binary:
await ws.send_bytes(
elif msg.type == web.WSMsgType.close:

return ws

app = web.Application()
app.add_routes([web.get('/', handle),
web.get('/echo', wshandle),
web.get('/{name}', handle)])




External links

* `Third party libraries
* `Built with aiohttp
* `Powered by aiohttp

Feel free to make a Pull Request for adding your link to these pages!

Communication channels

*aio-libs* google group:!forum/aio-libs

Feel free to post your questions and ideas here.

*gitter chat*

We support `Stack Overflow
Please add *aiohttp* tag to your question there.


- Python >= 3.5.3
- async-timeout_
- attrs_
- chardet_
- multidict_
- yarl_

Optionally you may install the cChardet_ and aiodns_ libraries (highly
recommended for sake of speed).

.. _chardet:
.. _aiodns:
.. _attrs:
.. _multidict:
.. _yarl:
.. _async-timeout:
.. _cChardet:


``aiohttp`` is offered under the Apache 2 license.


The aiohttp community would like to thank Keepsafe
( for its support in the early days of
the project.

Source code

The latest developer version is available in a GitHub repository:


If you are interested in efficiency, the AsyncIO community maintains a
list of benchmarks on the official wiki:


You should *NOT* be adding new change log entries to this file, this
file is managed by towncrier. You *may* edit previous change logs to
fix problems like typo corrections or such.
To add a new change log entry, please see
we named the news folder "changes".

WARNING: Don't drop the next directive!

.. towncrier release notes start

3.5.0b1 (2018-12-20)


- The library type annotations are checked in strict mode now.
- Add support for setting cookies for individual request (`#2387 <>`_)
- Application.add_domain implementation (`#2809 <>`_)
- The default ``app`` in the request returned by ``test_utils.make_mocked_request``
can now have objects assigned to it and retrieved using the ``[]`` operator. (`#3174 <>`_)
- Make ``request.url`` accessible when transport is closed. (`#3177 <>`_)
- Add zlib_executor_size Response parameter to allow compression to run in a background executor to avoid blocking the main thread and potentially triggering health check failures. (`#3205 <>`_)
- Enable users to set `ClientTimeout` in `aiohttp.request` (`#3213 <>`_)
- Don't raise a warning if ``NETRC`` environment variable is not set and ``~/.netrc`` file
doesn't exist. (`#3267 <>`_)
- Add default logging handler to web.run_app

If the `Application.debug` flag is set and the default logger `aiohttp.access` is used, access logs will now be output using a `stderr` `StreamHandler` if no handlers are attached. Furthermore, if the default logger has no log level set, the log level will be set to `DEBUG`. (`#3324 <>`_)
- Add method argument to ``session.ws_connect()``.

Sometimes server API requires a different HTTP method for WebSocket connection establishment.

For example, ``Docker exec`` needs POST. (`#3378 <>`_)
- Create a task per request handling. (`#3406 <>`_)


- Enable passing `access_log_class` via `handler_args` (`#3158 <>`_)
- Return empty bytes with end-of-chunk marker in empty stream reader. (`#3186 <>`_)
- Accept ``CIMultiDictProxy`` instances for ``headers`` argument in ``web.Response``
constructor. (`#3207 <>`_)
- Don't uppercase HTTP method in parser (`#3233 <>`_)
- Make method match regexp RFC-7230 compliant (`#3235 <>`_)
- Add ``app.pre_frozen`` state to properly handle startup signals in sub-applications. (`#3237 <>`_)
- Enhanced parsing and validation of helpers.BasicAuth.decode. (`#3239 <>`_)
- Change imports from collections module in preparation for 3.8. (`#3258 <>`_)
- Ensure Host header is added first to ClientRequest to better replicate browser (`#3265 <>`_)
- Fix forward compatibility with Python 3.8: importing ABCs directly from the collections module will not be supported anymore. (`#3273 <>`_)
- Keep the query string by `normalize_path_middleware`. (`#3278 <>`_)
- Fix missing parameter ``raise_for_status`` for aiohttp.request() (`#3290 <>`_)
- Bracket IPv6 addresses in the HOST header (`#3304 <>`_)
- Fix default message for server ping and pong frames. (`#3308 <>`_)
- Fix tests/ typo and tests/autobahn/ duplicate loop def. (`#3337 <>`_)
- Fix false-negative indicator end_of_HTTP_chunk in StreamReader.readchunk function (`#3361 <>`_)
- Release HTTP response before raising status exception (`#3364 <>`_)
- Fix task cancellation when ``sendfile()`` syscall is used by static file handling. (`#3383 <>`_)
- Fix stack trace for ``asyncio.TimeoutError`` which was not logged, when it is caught
in the handler. (`#3414 <>`_)

Improved Documentation

- Improve documentation of ``Application.make_handler`` parameters. (`#3152 <>`_)
- Fix BaseRequest.raw_headers doc. (`#3215 <>`_)
- Fix typo in TypeError exception reason in ``web.Application._handle`` (`#3229 <>`_)
- Make server access log format placeholder %b documentation reflect
behavior and docstring. (`#3307 <>`_)

Deprecations and Removals

- Deprecate modification of ``session.requote_redirect_url`` (`#2278 <>`_)
- Deprecate ``stream.unread_data()`` (`#3260 <>`_)
- Deprecated use of boolean in ``resp.enable_compression()`` (`#3318 <>`_)
- Encourage creation of aiohttp public objects inside a coroutine (`#3331 <>`_)
- Drop dead ``Connection.detach()`` and ``Connection.writer``. Both methods were broken
for more than 2 years. (`#3358 <>`_)
- Deprecate ``app.loop``, ``request.loop``, ``client.loop`` and ``connector.loop`` properties. (`#3374 <>`_)
- Depreacte explicit debug argument. Use asyncio debug mode instead. (`#3381 <>`_)
- Deprecate body parameter in HTTPException (and derived classes) constructor. (`#3385 <>`_)
- Deprecate bare connector close, use ``async with connector:`` and ``await connector.close()`` instead. (`#3417 <>`_)
- Deprecate obsolete ``read_timeout`` and ``conn_timeout`` in ``ClientSession`` constructor. (`#3438 <>`_)


- #3341, #3351

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