Struct axum::extract::WebSocketUpgrade

pub struct WebSocketUpgrade<F = DefaultOnFailedUpgrade> { /* private fields */ }

Extractor for establishing WebSocket connections.

Note: This extractor requires the request method to be GET so it should always be used with get. Requests with other methods will be rejected.

See the module docs for an example.

Implementations

impl<F> WebSocketUpgrade<F>

pub 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.

pub 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.

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

Set the maximum message size (defaults to 64 megabytes)

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

Set the maximum frame size (defaults to 16 megabytes)

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

Allow server to accept unmasked frames (defaults to false)

pub 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::get,
    response::{IntoResponse, Response},
    Router,
};

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

async fn handler(ws: WebSocketUpgrade) -> Response {
    ws.protocols(["graphql-ws", "graphql-transport-ws"])
        .on_upgrade(|socket| async {
            // ...
        })
}

pub 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 { /* ... */ })
}

pub 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.

Trait Implementations

impl<F> Debug for WebSocketUpgrade<F>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<S> FromRequestParts<S> for WebSocketUpgrade<DefaultOnFailedUpgrade>

where S: Send + Sync,

type Rejection = WebSocketUpgradeRejection

If the extractor fails it’ll use this “rejection” type. A rejection is a kind of error that can be converted into a response.

fn from_request_parts<'life0, 'life1, 'async_trait>( parts: &'life0 mut Parts, _state: &'life1 S, ) -> Pin<Box<dyn Future<Output = Result<Self, Self::Rejection>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Perform the extraction.