Shout-out is designed to work with FastAPI websocket, while running behind Gunicorn with multiple Uvicorn workers. Where a centralized caching layer (Redis) is required to maintain state (messages) across workers.
You can also use Shoutout as a standalone asynchronous application.
pip install shoutout-pyimport asyncio
from shoutout.broadcast import Broadcast
broadcast = Broadcast("redis://localhost:6379")
async def main():
await broadcast.connect()
async with broadcast.subscribe("hello") as subscriber:
if subscriber:
await broadcast.publish("hello", message={
"channel": "hello", "message": "Hello World!"})
async for _, msg in subscriber:
print(msg)
break
if __name__ == "__main__":
asyncio.run(main())The example above is complete and should run as is.
from fastapi import FastAPI, WebSocket
from fastapi.responses import HTMLResponse
from shoutout.broadcast import Broadcast
from starlette.concurrency import run_until_first_complete
broadcast = Broadcast("redis://localhost:6379")
app = FastAPI(on_startup=[broadcast.connect], on_shutdown=[broadcast.disconnect])
async def ws_receiver(websocket):
async for message in websocket.iter_text():
await broadcast.publish(channel="shout", message={"msg": message})
async def ws_sender(websocket):
async with broadcast.subscribe(channel="shout") as subscriber:
if subscriber:
async for _, msg in subscriber:
await websocket.send_json(msg)
@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
await websocket.accept()
await run_until_first_complete(
(ws_receiver, {"websocket": websocket}),
(ws_sender, {"websocket": websocket}),
)
html = """
<!DOCTYPE html>
<html>
<head>
<title>Chat</title>
</head>
<body>
<h1>WebSocket Chat</h1>
<form action="" onsubmit="sendMessage(event)">
<input type="text" id="messageText" autocomplete="off"/>
<button>Send</button>
</form>
<ul id='messages'>
</ul>
<script>
var ws = new WebSocket("ws://localhost:8000/ws");
ws.onmessage = function(event) {
var messages = document.getElementById('messages')
var message = document.createElement('li')
var content = document.createTextNode(event.data)
message.appendChild(content)
messages.appendChild(message)
};
function sendMessage(event) {
var input = document.getElementById("messageText")
ws.send(input.value)
input.value = ''
event.preventDefault()
}
</script>
</body>
</html>
"""
@app.get("/")
async def get():
return HTMLResponse(html)The example above is complete and should run as is.
Run it:
uvicorn main:app --reload