How does websockets handle ping-pong keepalive mechanism exactly with ping receivement?

[mick-liu]

Dear aaugustin,

I just have a simple question about the following description that you said "websockets takes care of responding to pings with pongs." But I want to know more how does it work? For example, if I have received a ping from our connected server, would it automatically send pong back or something? And how?

Thank you for the work of creating this amazing packages.
Sincerely,.

reference: https://websockets.readthedocs.io/en/stable/faq/common.html#how-do-i-respond-to-pings

[aaugustin]

Yes, "websockets takes care of responding to pings with pongs." means that it is done automatically.

It is done according to https://www.rfc-editor.org/rfc/rfc6455#page-37:

Upon receipt of a Ping frame, an endpoint MUST send a Pong frame in
response, unless it already received a Close frame. It SHOULD
respond with Pong frame as soon as is practical. Pong frames are
discussed in Section 5.5.3.

A Pong frame sent in response to a Ping frame must have identical
"Application data" as found in the message body of the Ping frame
being replied to.

[aaugustin]

You might be referring to a custom application-level keepalive mechanism while I'm talking of the standard protocol-level mechanism. I will clarify the FAQ.

[mick-liu]

Thank you, I know how it works now.