PhotonImplemented

Realtime product state

Photon is a Rust pub/sub runtime with typed topics and durable subscriptions. Storage is pluggable, with memory, SQLite, NATS, Fluvio, and Kafka adapters, and the same publish and subscribe code runs embedded or brokered.

Photon topic page for counter.updated with its recent events highlighted — Each topic page lists its subscriptions and the latest events published to it.

Ships inEmbedded Remote fleet

Works withValence·Higgs·Orbital

Why it exists

Photon gives you typed topics and subscriptions while your data stays in your datastore. The transport carries short-lived, encrypted events, and the browser refetches the data it shows when one arrives.

On this site

Photon pushes updates to the counter demo and the notification bell on this site. It notifies the UI; Valence or your datastore remains authoritative.

Implemented

Declare topic payloads and subscriber handlers through #[topic] and #[subscribe].

Implemented

Checkpoint sequence positions per partition for subscribers that must resume after restart.

Implemented

Partition and filter event streams by declared payload keys.

Implemented

Run on memory or SQLite, or connect NATS, Fluvio, and Kafka for fleet deployments.

Implemented

Mark a server function with #[photon_leptos::synced] and choose whether the browser refetches, replaces or appends when the topic fires.

Implemented

Set one retention policy for the runtime: maximum event age, sweep interval, and whether dead letters are kept. Kafka and Fluvio handle retention on the broker.

Implemented

Inspect topics, subscriptions, and events from the runtime on this host at /photon.

See it in action

Events

Browse recent events across every topic.

Implemented

Code sample

Taken from the getting-started docs. See all code samples on Resources.

Photon topicPhoton

Typed topic + durable subscribe

use std::sync::Arc;
use photon::{subscribe, topic, JsonIdentityFactory, Photon};
use photon_core::Actor;

#[topic(name = "orders.created", keyed_by = "order_id")]
pub struct OrderCreated {
    pub order_id: String,
    pub amount_cents: u64,
}

#[subscribe(topic = "orders.created", durable = "billing")]
async fn on_order_created(actor: Box<dyn Actor>, event: OrderCreated) -> photon::Result<()> {
    tracing::info!(actor = actor.label(), order = %event.order_id, cents = event.amount_cents);
    Ok(())
}

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    // Requires PHOTON_TRANSPORT_KEY (base64, 32 bytes).
    let photon = Photon::builder().auto_registry().build()?;
    photon.start_executor(Arc::new(JsonIdentityFactory))?;

    OrderCreated {
        order_id: "ord-1".into(),
        amount_cents: 9900,
    }
    .publish_on(&photon)
    .await?;
    Ok(())
}

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