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Send a websocket pong control frame asynchronously.

    class WriteHandler = net::default_completion_token_t<executor_type>>
    ping_data const& payload,
    WriteHandler&& handler = net::default_completion_token_t< executor_type >{});

This function is used to asynchronously send a pong frame, which is usually sent automatically in response to a ping frame from the remote peer.

The algorithm, known as a composed asynchronous operation, is implemented in terms of calls to the next layer's async_write_some function. The program must ensure that no other calls to ping, pong, async_ping, or async_pong are performed until this operation completes. If a close frame is sent or received before the pong frame is sent, the error received by this completion handler will be net::error::operation_aborted. WebSocket allows pong frames to be sent at any time, without first receiving a ping. An unsolicited pong sent in this fashion may indicate to the remote peer that the connection is still active.





The payload of the pong message, which may be empty. The implementation will not access the contents of this object after the initiating function returns.


The completion handler to invoke when the operation completes. The implementation takes ownership of the handler by performing a decay-copy. The equivalent function signature of the handler must be:

void handler(
    error_code const& ec     // Result of operation

Regardless of whether the asynchronous operation completes immediately or not, the handler will not be invoked from within this function. Invocation of the handler will be performed in a manner equivalent to using net::post.

Per-Operation Cancellation

This asynchronous operation supports cancellation for the following net::cancellation_type values:

totalcancellation succeeds if the operation is suspended due to ongoing control operations such as a ping/pong. terminal cancellation succeeds when supported by the underlying stream. terminal cancellation leaves the stream in an undefined state, so that only closing it is guaranteed to succeed.