Photon

Feature flags, wiring, and verify commands for adding Photon to a Rust service. Project overview: README.

Install

crates.io package uf-photon (Rust crate name remains photon):

photon = { package = "uf-photon", version = "0.1.0", features = ["runtime", "mem"] }

Features

Configuration reference: docs.rs photon::config. Architecture: docs.rs photon.

Ships with no default features (default = []). Enable runtime + mem for the standard evaluation path.

Wiring

1. Build with Photon::builder() — default installs InProcStoragePort (mem). Requires PHOTON_TRANSPORT_KEY (TransportCrypto::from_env).
2. Optionally pass .storage_port(Arc<dyn StoragePort>) for sqlite or broker adapters.
3. Call .auto_registry() when using #[photon::topic] / #[photon::subscribe].
4. Keep the Photon handle and call publish_on(&photon) / subscribe_on(&photon, opts) (preferred).
5. Optional: photon::configure(photon) for process-wide .publish() / .subscribe() sugar.
6. Call photon.start_executor(identity) when using #[photon::subscribe] handlers.

Default bootstrap (mem)

use photon::Photon;

// Loads PHOTON_TRANSPORT_KEY via from_env().
let photon = Photon::builder().auto_registry().build()?;
// EventType { ... }.publish_on(&photon).await?;
// Optional: configure(photon) for .publish() without a handle.

Custom storage port

use std::sync::Arc;

use photon::Photon;
use photon_backend::storage::InProcStoragePort;
use photon_backend::event::TransportCrypto;

let port = Arc::new(InProcStoragePort::new(TransportCrypto::from_env()?));
let photon = Photon::builder()
    .storage_port(port)
    .auto_registry()
    .build()?;

Broker env vars and builder options: each adapter's *StoragePortBuilder rustdoc (linked from photon::config).

SQLite — durable single-process

Write-through persistence with in-memory live fanout (no external broker):

use std::sync::Arc;

use photon::{Photon, SqliteStoragePort};

let port = Arc::new(SqliteStoragePort::open("/var/lib/photon/events.db").await?);
// Or: SqliteStoragePort::from_env().await?  // reads PHOTON_SQLITE_PATH
let photon = Photon::builder()
    .storage_port(port)
    .auto_registry()
    .build()?;

See photon-backend-sqlite.

NATS JetStream — production (durable)

Durable subscriptions, checkpoint replay, and stream-sharded fleet ingress:

use std::sync::Arc;

use photon::{Photon, NatsStoragePort, ReplayCursor};

let port = Arc::new(
    NatsStoragePort::builder()
        .from_env_defaults()
        .replay_cursor(ReplayCursor::StreamSeq)
        .sync_ack(true)
        .stream_shards(4) // match broker count; rep=1 per shard when K>1
        .build()
        .await?,
);
let photon = Photon::builder()
    .storage_port(port)
    .auto_registry()
    .build()?;

NATS JetStream — high ingress (ephemeral)

Maximum publish throughput when durable replay and checkpoints are not required:

use std::sync::Arc;

use photon::{Photon, NatsStoragePort, ReplayCursor};

let port = Arc::new(
    NatsStoragePort::builder()
        .from_env_defaults()
        .replay_cursor(ReplayCursor::TailOnly)
        .sync_ack(false)
        .max_inflight(256)
        .stream_shards(4)
        .build()
        .await?,
);
let photon = Photon::builder()
    .storage_port(port)
    .auto_registry()
    .build()?;

Builder fields and env fallbacks: NatsStoragePortBuilder rustdoc.

Verify

Prefer AWS when local cargo is unavailable: ../infra/aws/sqlite-smoke/scripts/run-remote-check.sh.

export PHOTON_TRANSPORT_KEY=cGhvdG9uLWRldi10cmFuc3BvcnQta2V5LTMyYnl0ZXM=
cargo check -p uf-photon --features runtime,mem
cargo run -p uf-photon --example embedded_mem --features runtime,mem
cargo test -p uf-photon --doc --features runtime,mem

Full matrix: root README § Verify. Macro expansion: docs/macro-expansion.md.