Support for Websocket Ping to check connection status and clean up stale connections

[TheNotary]

Privileged issue

• I'm @tiangolo or he asked me directly to create an issue here.

Issue Content

I just read #626, and it seems like handling ping was discussed and resolved, but nothing was mentioned around sending a ping out to a client. I believe that would test the connection and allow a WebsocketDiscconnect exception to be thrown allowing the connection to be cleaned up. It seems though that the websocket I'm referencing doesn't expose a .conn attribute so I don't understand how to send a ping. Could someone provide a more explicit explanation around invoking websocket ping from the server to validate connections?

[jgould22]

Based on the linked issue, as tiangelo pointed out the response is not handled at the application level (ie. in your FastAPI code).

In this case you do nothing. Uvicorn (or whatever asgi server) is responsible for returning the pong message.