Brokers

A broker connects RustStream to a message transport. The framework ships an in-memory broker for development and tests; production brokers are separate crates you add as a dependency.

Handlers, routers, codecs, and middleware are broker-agnostic, so moving between brokers is a one-line change at with_broker.

Broker	Crate	Transport
Memory	ruststream (feature memory)	in-process, for development and tests
NATS	ruststream-nats	Core NATS and JetStream

To implement a broker for another transport, see Broker authors.

Switching brokers

Every broker constructs synchronously and connects lazily (the runtime calls Broker::connect once at startup), so the same handlers and routers run on any of them; only the broker construction differs by one line inside with_broker.

MemoryNATS

use ruststream::memory::MemoryBroker;
use ruststream::runtime::{AppInfo, RustStream};

#[ruststream::app]
fn app() -> RustStream {
    RustStream::new(AppInfo::new("orders", "0.1.0"))
        .with_broker(MemoryBroker::new(), |b| b.include_router(routes::orders()))
}

use ruststream::runtime::{AppInfo, RustStream};
use ruststream_nats::NatsBroker;

#[ruststream::app]
fn app() -> RustStream {
    RustStream::new(AppInfo::new("orders", "0.1.0"))
        .with_broker(NatsBroker::new("nats://localhost:4222"), |b| {
            b.include_router(routes::orders())
        })
}

Subscriptions that need broker-specific options (consumer groups, durable names) use that broker's descriptor in the #[subscriber(..)] decorator; see broker-specific descriptors.