Websockets

Sanic provides an easy to use abstraction on top of websockets (opens new window).

Routing

Websocket handlers can be hooked up to the router similar to regular handlers.

from sanic import Request, Websocket
async def feed(request: Request, ws: Websocket):
    pass
app.add_websocket_route(feed, "/feed")

from sanic import Request, Websocket
@app.websocket("/feed")
async def feed(request: Request, ws: Websocket):
    pass

Handler

Typically, a websocket handler will want to hold open a loop.

It can then use the send() and recv() methods on the second object injected into the handler.

This example is a simple endpoint that echos back to the client messages that it receives.

from sanic import Request, Websocket
@app.websocket("/feed")
async def feed(request: Request, ws: Websocket):
    while True:
        data = "hello!"
        print("Sending: " + data)
        await ws.send(data)
        data = await ws.recv()
        print("Received: " + data)

You can simplify your loop by just iterating over the Websocket object in a for loop.

Added in v22.9

from sanic import Request, Websocket
@app.websocket("/feed")
async def feed(request: Request, ws: Websocket):
    async for msg in ws:
        await ws.send(msg)

Configuration

See configuration section for more details, however the defaults are shown below.

app.config.WEBSOCKET_MAX_SIZE = 2 ** 20
app.config.WEBSOCKET_PING_INTERVAL = 20
app.config.WEBSOCKET_PING_TIMEOUT = 20