aio-libs/aiohttp

How aio-libs/aiohttp works

aiohttp is an asyncio HTTP client/server framework, with WebSocket support on both sides. Its client workflow builds a request, obtains a connection, exchanges HTTP data, and exposes a response; its server workflow accepts a request, dispatches a route through middleware to a handler, and sends a response. WebSocket handling branches from HTTP upgrade on each side. The tree and README establish these capabilities; sampled excerpts chiefly confirm client request/response, connector, and frame-processing responsibilities, so uncertain internal links are omitted.

Main entry points: client.py Client session · client_reqrep.py Client request/response · web_app.py Application and routes · web_protocol.py Server protocol

Components 26

HTTP client

Client session aiohttp/client.py
Client request/response aiohttp/client_reqrep.py
Connection pool aiohttp/connector.py
Client protocol aiohttp/client_proto.py
Digest middleware aiohttp/client_middleware_digest_auth.py

HTTP server

Application and routes aiohttp/web_app.py
Server middleware aiohttp/web_middlewares.py
URL dispatcher aiohttp/web_urldispatcher.py
Server request aiohttp/web_request.py
Server response aiohttp/web_response.py
Server protocol aiohttp/web_protocol.py
Server lifecycle aiohttp/web_server.py

HTTP and streams

HTTP parser aiohttp/http_parser.py
HTTP writer aiohttp/http_writer.py
Async streams aiohttp/streams.py

WebSocket

Client WebSocket aiohttp/client_ws.py
Server WebSocket aiohttp/web_ws.py
Frame reader aiohttp/_websocket/reader.py
Frame writer aiohttp/_websocket/writer.py

Request support

Payload encoding aiohttp/payload.py
Multipart forms aiohttp/multipart.py
Cookie jar aiohttp/cookiejar.py

Other components

Application code
Remote HTTP peer
Incoming HTTP peer
Route handler

Connections 31

Application code → Client session: requests through
Client session → Client request/response: creates and sends
Client session → Connection pool: acquires connection
Client request/response → Connection pool: sends request
Connection pool → Remote HTTP peer: exchanges transport data
Client protocol → HTTP parser: parses response data
HTTP parser → Async streams: feeds body bytes
Client request/response → Payload encoding: encodes request body
Client session → Cookie jar: manages cookies
Digest middleware → Client session: middleware integration
Incoming HTTP peer → Server lifecycle: connects to
Server lifecycle → Server protocol: serves protocol
Server protocol → HTTP parser: parses request data
HTTP parser → Server request: provides parsed request
Server protocol → Application and routes: dispatches request
Application and routes → Server middleware: applies middleware
Application and routes → URL dispatcher: resolves route
URL dispatcher → Route handler: invokes handler
Route handler → Server response: returns response
Server protocol → HTTP writer: writes response
Server response → HTTP writer: serializes response
HTTP writer → Remote HTTP peer: sends HTTP data
Application and routes → Server WebSocket: supports upgrade handler
Client session → Client WebSocket: initiates upgrade
Client WebSocket → Frame reader: reads frames
Client WebSocket → Frame writer: writes frames
Server WebSocket → Frame reader: reads frames
Server WebSocket → Frame writer: writes frames
Frame reader → Async streams: queues messages
Frame writer → Remote HTTP peer: sends frames
Client request/response → Multipart forms: parses disposition

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Drawn by GitDiagram on September 25, 2026 from the repository's file tree, README and source files. Read as Markdown ·