Leptos Server Sent Events

Server signals are leptos signals kept in sync with the server through server-sent-events (SSE).

The signals are read-only on the client side, and can be written to by the server. This is useful if you want real-time updates on the UI controlled by the server.

Changes to a signal are sent through a SSE to the client as json patches.

This project is heavily based on leptos_server_signal.

Feature flags

• ssr: ssr is enabled when rendering the app on the server.
• actix: integration with the Actix web framework.
• axum: integration with the Axum web framework.

Example

Cargo.toml

[dependencies]
leptos_sse = "*"
serde = { version = "*", features = ["derive"] }

[features]
ssr = [
  "leptos_sse/ssr",
  "leptos_sse/axum", # or actix
]

Client

use leptos::*;
use leptos_sse::create_sse_signal;
use serde::{Deserialize, Serialize};

#[derive(Clone, Default, Serialize, Deserialize)]
pub struct Count {
    pub value: i32,
}

#[component]
pub fn App() -> impl IntoView {
    // Provide SSE connection
    leptos_sse::provide_sse("http://localhost:3000/sse").unwrap();

    // Create server signal
    let count = create_sse_signal::<Count>("counter");

    view! {
        <h1>"Count: " {move || count().value.to_string()}</h1>
    }
}

If on stable, use count.get().value instead of count().value.

Server (Axum)

#[cfg(feature = "ssr")]
use {
    axum::response::sse::{Event, KeepAlive, Sse},
    futures::stream::Stream,
};

#[cfg(feature = "ssr")]
async fn handle_sse() -> Sse<impl Stream<Item = Result<Event, axum::BoxError>>> {
    use futures::stream;
    use leptos_sse::ServerSentEvents;
    use std::time::Duration;
    use tokio_stream::StreamExt as _;

    let mut value = 0;
    let stream = ServerSentEvents::new(
        "counter",
        stream::repeat_with(move || {
            let curr = value;
            value += 1;
            Ok(Count { value: curr })
        })
        .throttle(Duration::from_secs(1)),
    )
    .unwrap();
    Sse::new(stream).keep_alive(KeepAlive::default())
}

License

This work is released under the MIT license. A copy of the license is provided in the LICENSE file.