WebSocket

Processor

In the following text, the callable object used to handle WebSocket requests is referred to as a WebSocket processor.

Function Processor

At the beginning of a WebSocket processor, you must call await websocket.accept(), and when the processor exits, you must call await websocket.close(CLOSE_CODE).

from kui.asgi import websocket


async def simple_echo():
    await websocket.accept()
    try:
        while True:
            message = await websocket.receive_json()
            await websocket.send_json(message)
    finally:
        await websocket.close(1000)

Class Processor

Similar to HTTP class processors, WebSocket class processors can inherit from kui.asgi.SocketView.

It has a class attribute: encoding, which can have several available values - "anystr", "text", "bytes", "json", determining how the received WebSocket data is parsed. The default value is anystr.

It has three methods for regular usage, corresponding to different states of a WebSocket connection:

1. on_connect()

   This function is called after a WebSocket connection is established.

   If you override this function, you must explicitly call await websocket.accept() within it to accept the connection.

2. on_receive(data: typing.Any)

   This function is called when a complete data is received, and the type of data is controlled by the class attribute encoding.

3. on_disconnect(close_code: int)

   This function is called when a WebSocket is about to be closed.

   If you override this function, you must explicitly call await websocket.close(code=close_code) within it to close the connection.

Notice

All three functions must be defined as asynchronous functions using async def.