Crate stan

NATS Streaming client wrapper built on top of NATS.rs

Warning: still early stage of development, although feature complete. Contributions and feedback more than welcome!

Examples

use nats;
use std::{io, str::from_utf8, time};

fn main() -> io::Result<()> {
    let nc = nats::connect("nats://127.0.0.1:4222")?;
    let sc = stan::connect(nc, "test-cluster", "rust-client-1")?;

    sc.publish("foo", "hello from rust 1")?;

    sc.subscribe("foo", Default::default())?
        .with_handler(|msg| {
            println!("sub 1 got {:?}", from_utf8(&msg.data));
            Ok(())
        });

    let sub = sc
        .subscribe(
            "foo",
            stan::SubscriptionConfig {
                queue_group: Some("queue-group-name"),
                durable_name: Some("my-durable-queue"),
                start: stan::SubscriptionStart::AllAvailable,
                ..Default::default()
            },
        )?
        .with_handler(|msg| {
            println!("sub 2 got {:?}", from_utf8(&msg.data));
            msg.ack()?;
            println!("manually acked!");
            Ok(())
        });

    for msg in sc.subscribe("foo", Default::default())?.messages() {
        println!("sub 3 got {:?}", from_utf8(&msg.data));
        msg.ack()?;
        break; // just break for the example to run
    }

    for msg in sc
        .subscribe("foo", Default::default())?
        .timeout_iter(time::Duration::from_secs(1))
    {
        println!("sub 4 got {:?}", from_utf8(&msg.data));
        msg.ack()?;
        break; // just break for the example to run
    }

    sc.publish("foo", "hello from rust 2")?;
    sc.publish("foo", "hello from rust 3")?;

    sub.unsubscribe()?;

    sc.publish("foo", "hello from rust 4")?;
    Ok(())
}

Rationale

We were interested in at-least-once delivery with NATS, and the options here today are NATS Streaming, Lightbridge or Jetstream.

Jetstream is the future of at-least-once delivery on NATS, but is still in tech preview, while NATS Streaming has been battle tested in production.

At the same time, the NATS team is providing an awesome rust client that also has support for Jetstream, but they are not planning on supporting NATS Streaming (reasonable since Jetstream is around the corner).

Since NATS Streaming is just a layer on top of NATS, this library was written to just wrap the nats.rs client to handle the NATS Streaming protocol, for those like us stuck with NATS Streaming until Jetstream is production ready.

Structs

Client	NATS Streaming client
IntoIter	An iterator over messages from a Subscription
Iter	An iterator over messages from a Subscription
Message	NATS Streaming message received on subscriptions
Subscription	NATS Streaming subscription
SubscriptionConfig	Configuration to pass to subscription. Defaults to no queue group, no durable queue and starts from last received message.
TimeoutIter	An iterator over messages from a Subscription where None will be returned if a new Message has not been received by the end of a timeout.
TryIter	A non-blocking iterator over messages from a Subscription

Enums

SubscriptionStart

Functions

connect