Websockets

Sanic provides an easy to use abstraction on top of websockets.

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