impl<F> WebSocketUpgrade<F>

fn read_buffer_size(self, size: usize) -> Self

Read buffer capacity. The default value is 128KiB

fn write_buffer_size(self, size: usize) -> Self

The target minimum size of the write buffer to reach before writing the data to the underlying stream.

The default value is 128 KiB.

If set to 0 each message will be eagerly written to the underlying stream. It is often more optimal to allow them to buffer a little, hence the default value.

Note: flush will always fully write the buffer regardless.

fn max_write_buffer_size(self, max: usize) -> Self

The max size of the write buffer in bytes. Setting this can provide backpressure in the case the write buffer is filling up due to write errors.

The default value is unlimited.

Note: The write buffer only builds up past write_buffer_size when writes to the underlying stream are failing. So the write buffer can not fill up if you are not observing write errors even if not flushing.

Note: Should always be at least write_buffer_size + 1 message and probably a little more depending on error handling strategy.

fn max_message_size(self, max: usize) -> Self

Set the maximum message size (defaults to 64 megabytes)

fn max_frame_size(self, max: usize) -> Self

Set the maximum frame size (defaults to 16 megabytes)

fn accept_unmasked_frames(self, accept: bool) -> Self

Allow server to accept unmasked frames (defaults to false)

fn protocols<I>(self, protocols: I) -> Self
where
    I: IntoIterator,
    I::Item: Into<Cow<'static, str>>,

Set the known protocols.

If the protocol name specified by Sec-WebSocket-Protocol header to match any of them, the upgrade response will include Sec-WebSocket-Protocol header and return the protocol name.

The protocols should be listed in decreasing order of preference: if the client offers multiple protocols that the server could support, the server will pick the first one in this list.

Examples

use axum::{
    extract::ws::{WebSocketUpgrade, WebSocket},
    routing::any,
    response::{IntoResponse, Response},
    Router,
};

let app = Router::new().route("/ws", any(handler));

async fn handler(ws: WebSocketUpgrade) -> Response {
    ws.protocols(["graphql-ws", "graphql-transport-ws"])
        .on_upgrade(|socket| async {
            // ...
        })
}
# let _: Router = app;

fn requested_protocols(&self) -> impl Iterator<Item = &HeaderValue>

Return the WebSocket subprotocols requested by the client.

Examples

If the client sends the following HTTP header in the WebSocket upgrade request:

Sec-WebSocket-Protocol: soap, wamp

this method returns an iterator yielding "soap" and "wamp".

fn set_selected_protocol(&mut self, protocol: HeaderValue)

Set the chosen WebSocket subprotocol.

Another method, [protocols()][Self::protocols], also sets the chosen WebSocket subprotocol. If both methods are called, only the latter call takes effect.

Notes

• The chosen protocol is echoed back in the WebSocket upgrade response as required by RFC 6455. Some browsers may reject a value that was not present in the client's request.

fn selected_protocol(&self) -> Option<&HeaderValue>

Return the selected WebSocket subprotocol, if one has been chosen.

If [protocols()][Self::protocols] selects a matching protocol, or [set_selected_protocol()][Self::set_selected_protocol] has been called, the return value will be Some containing the selected protocol. Otherwise, it will be None.

fn on_failed_upgrade<C>(self, callback: C) -> WebSocketUpgrade<C>
where
    C: OnFailedUpgrade,

Provide a callback to call if upgrading the connection fails.

The connection upgrade is performed in a background task. If that fails this callback will be called.

By default any errors will be silently ignored.

Example

use axum::{
    extract::{WebSocketUpgrade},
    response::Response,
};

async fn handler(ws: WebSocketUpgrade) -> Response {
    ws.on_failed_upgrade(|error| {
        report_error(error);
    })
    .on_upgrade(|socket| async { /* ... */ })
}
#
# fn report_error(_: axum::Error) {}

fn on_upgrade<C, Fut>(self, callback: C) -> Response
where
    C: FnOnce(WebSocket) -> Fut + Send + 'static,
    Fut: Future<Output = ()> + Send + 'static,
    F: OnFailedUpgrade,

Finalize upgrading the connection and call the provided callback with the stream.