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WebSockets

Yaat also supports sending and receiving data on a WebSocket.

WebSocket

WebSocket(scope, receive, send)

It provides an interface to talk with the ASGI server. It has similar properties as Request.

• url - string-like object with all components parsed out from the URL.
• headers - returns Headers dictionary. You can access the individual value just like accessing a dictionary.
• query_params - returns QueryParams dictionary. You can access the individual value like a dictionary.

Accept Connection

You can accept the WebSocket connection by calling accept().

await websocket.accept(subprotocol=None)

Sending Data

• await websocket.send_text(data)
  • data - a string data.
• await websocket.send_bytes(data)
  • data - bytes data.
• await websocket.send_json(data, mode="text")
  • data - a dictionary object.
  • mode - to send data in text and bytes. 2 modes available (text, bytes). Send in text by default.

Receiving Data

• await websocket.receive_text()
• await websocket.receive_bytes()
• await websocket.receive_json(mode="text")
  • data - a dictionary object.
  • mode - to receive data in text and bytes. 2 modes available (text, bytes). Receive in text by default.

Sending Raw Messages

If you want to send raw ASGI messages you can call send().

• await websocket.send(message)

Receiving Raw Messages

If you want to receive raw ASGI messages you can call receive().

• await websocket.receive()

Close Connection

You can close the connection by calling close().

• await websocket.close(code=1000)
  • code - websocket close event

If you want to use different close event, you can enter the code number or import the constant.

from yaat.constants import WebSocketCloseEvent as WsClose

...
    await websocket.close(WsClose.ABNORMAL_CLOSURE)
...

class WebSocketCloseEvent:
    # https://developer.mozilla.org/en-US/docs/Web/API/CloseEvent

    NORMAL_CLOSURE = 1000
    GOING_AWAY = 1001
    PROTOCOL_ERROR = 1002
    UNSUPPORTED_DATA = 1003
    NO_STATUS_RECEIVED = 1005
    ABNORMAL_CLOSURE = 1006
    INVALID_FRAME_PAYLOAD_DATA = 1007
    POLICY_VIOLATION = 1008
    MESSAGE_TOO_BIG = 1009
    MISSING_EXTENSION = 1010
    INTERNAL_ERROR = 1011
    SERVICE_RESTART = 1012
    TRY_AGAIN_LATER = 1013
    BAD_GATEWAY = 1014
    TLS_HANDSHAKE = 1015

WebSocket Route

Yaat also comes with a separate decorator to indicates WebSocket endpoints. When the request comes in, the router will pass the WebSocket class to the endpoint.

@app.websocket_route("/ws")
async def ws_handler(websocket):
    await websocket.accept()
    await websocket.send_text("Hello")
    await websocket.close()

You can also register WebSocket endpoints via add_websocket_route.

add_websocket_route(path, handler)

• path - url of the endpoint.
• handler - WebSocket endpoint method.

async def ws_handler(websocket):
    await websocket.accept()
    await websocket.send_text("Hello")
    await websocket.close()

app.add_websocket_route(ws_handler)

Mounting WebSocket Routes

If you have to mount the WebSocket application, you can just indicate websocket=True to mount().

app.mount(prefix="ws", router=WebSocketRouter, websocket=True)