Client

To retrieve something from the web:

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, 'http://python.org')
        print(html)

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

Server

This is simple usage example:

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(msg.data))
        elif msg.type == web.WSMsgType.binary:
            await ws.send_bytes(msg.data)
        elif msg.type == web.WSMsgType.close:
            break

    return ws


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

web.run_app(app)

Features

• Add type hints (#3049)
• Add raise_for_status request parameter (#3073)
• Add type hints to HTTP client (#3092)
• Minor server optimizations (#3095)
• Preserve the cause when HTTPException is raised from another exception. (#3096)
• Add close_boundary option in MultipartWriter.write method. Support streaming (#3104)
• Added a remove_slash option to the normalize_path_middleware factory. (#3173)
• The class AbstractRouteDef is importable from aiohttp.web. (#3183)

Bugfixes

• Prevent double closing when client connection is released before the last data_received() callback. (#3031)
• Make redirect with normalize_path_middleware work when using url encoded paths. (#3051)
• Postpone web task creation to connection establishment. (#3052)
• Fix sock_read timeout. (#3053)
• When using a server-request body as the data= argument of a client request, iterate over the content with readany instead of readline to avoid Line too long errors. (#3054)
• fix UrlDispatcher has no attribute add_options, add web.options (#3062)
• correct filename in content-disposition with multipart body (#3064)
• Many HTTP proxies has buggy keepalive support. Let’s not reuse connection but close it after processing every response. (#3070)
• raise 413 “Payload Too Large” rather than raising ValueError in request.post() Add helpful debug message to 413 responses (#3087)
• Fix StreamResponse equality, now that they are MutableMapping objects. (#3100)
• Fix server request objects comparison (#3116)
• Do not hang on 206 Partial Content response with Content-Encoding: gzip (#3123)
• Fix timeout precondition checkers (#3145)

Improved Documentation

• Add a new FAQ entry that clarifies that you should not reuse response objects in middleware functions. (#3020)
• Add FAQ section “Why is creating a ClientSession outside of an event loop dangerous?” (#3072)
• Fix link to Rambler (#3115)
• Fix TCPSite documentation on the Server Reference page. (#3146)
• Fix documentation build configuration file for Windows. (#3147)
• Remove no longer existing lingering_timeout parameter of Application.make_handler from documentation. (#3151)
• Mention that app.make_handler is deprecated, recommend to use runners API instead. (#3157)

Deprecations and Removals

• Drop loop.current_task() from helpers.current_task() (#2826)
• Drop reader parameter from request.multipart(). (#3090)