Ratsio

Ratsio is a Rust client library for NATS messaging system and NATS Event Streaming.

Inspired by nitox and rust-nats but my project needed NATS streaming, so I couldn't use any of those 2. If this project is useful to you, feel free to contribute or suggest features. at the moment it's just the features I need.

Add the following to your Cargo.toml.

[dependencies]
ratsio = "0.3.0-alpha.4"

Rust -stable, -beta and -nightly are supported.

Features:

• Nats messaging queue. Publish, Subcribe and Request.
• Nats cluster support, auto reconnect
• Dynamic cluster hosts update.
• Async from the ground up, using tokio and futures.
• TLS mode
• NATS 1.x Authentication
• NATS 2.0 JWT-based client authentication
• NATS Streaming Server

Usage

Subscribing and Publishing to a NATS subject: see examples/nats_subscribe.rs

use ratsio::{NatsClient, RatsioError};
use log::info;
use futures::StreamExt;

pub fn logger_setup() {
    use log::LevelFilter;
    use std::io::Write;
    use env_logger::Builder;

    let _ = Builder::new()
        .format(|buf, record| {
            writeln!(buf,
                     "[{}] - {}",
                     record.level(),
                     record.args()
            )
        })
        .filter(None, LevelFilter::Trace)
        .try_init();
}


#[tokio::main]
async fn main() -> Result<(), RatsioError> {
    logger_setup();

    //Create nats client
    let nats_client = NatsClient::new("nats://localhost:4222").await?;
    
    //subscribe to nats subject 'foo'
    let (sid, mut subscription) = nats_client.subscribe("foo").await?;
    tokio::spawn(async move {
        //Listen for messages on the 'foo' description 
        //The loop terminates when the upon un_subscribe
        while let Some(message) = subscription.next().await {
            info!(" << 1 >> got message --- {:?}\n\t{:?}", &message,
                  String::from_utf8_lossy(message.payload.as_ref()));
        }
        info!(" << 1 >> unsubscribed. loop is terminated.")
    });

    //subscribe to nats subject 'foo', another subscription 
    let (_sid, mut subscription2) = nats_client.subscribe("foo").await?;
    tokio::spawn(async move {
        //Listen for messages on the 'foo' description
        while let Some(message) = subscription2.next().await {
            info!(" << 2 >> got message --- {:?}\n\t{:?}", &message,
                  String::from_utf8_lossy(message.payload.as_ref()));
        }
    });

    //Publish some messages, restart nats server during this time.
    use std::{thread, time};
    thread::sleep(time::Duration::from_secs(5));


    //Publish message
    let _ = nats_client.publish("foo", b"Publish Message 1").await?;
    thread::sleep(time::Duration::from_secs(1));

    //Unsubscribe
    let _ = nats_client.un_subscribe(&sid).await?;
    thread::sleep(time::Duration::from_secs(3));

    //Publish some messages.
    thread::sleep(time::Duration::from_secs(1));
    let _ = nats_client.publish("foo", b"Publish Message 2").await?;
    thread::sleep(time::Duration::from_secs(600));
    info!(" ---- done --- ");
    Ok(())
}

Subscribing and Publishing to a NATS streaming subject: see tests/stan_subscribe.rs

use log::info;
use futures::StreamExt;
use ratsio::{RatsioError, StanClient, StanOptions};

pub fn logger_setup() {
    use log::LevelFilter;
    use std::io::Write;
    use env_logger::Builder;

    let _ = Builder::new()
        .format(|buf, record| {
            writeln!(buf,
                     "[{}] - {}",
                     record.level(),
                     record.args()
            )
        })
        .filter(None, LevelFilter::Trace)
        .try_init();
}


#[tokio::main]
async fn main() -> Result<(), RatsioError> {
    logger_setup();
    // Create stan options
    let client_id = "test1".to_string();
    let opts = StanOptions::with_options("localhost:4222", "test-cluster", &client_id[..]);
    //Create STAN client
    let stan_client = StanClient::from_options(opts).await?;
    
    //Subscribe to STAN subject 'foo'
    let (sid, mut subscription) = stan_client.subscribe("foo", None, None).await?;
    tokio::spawn(async move {
        while let Some(message) = subscription.next().await {
            info!(" << 1 >> got stan message --- {:?}\n\t{:?}", &message,
                  String::from_utf8_lossy(message.payload.as_ref()));
        }
        info!(" ----- the subscription loop is done ---- ")
    });
    
    //Publish some mesesages to 'foo', use 'cargo run --example stan_publish foo "hi there"' 
    use std::{thread, time};
    thread::sleep(time::Duration::from_secs(60));
    
    //Unsubscribe 
    let _ = stan_client.un_subscribe(&sid).await;
    thread::sleep(time::Duration::from_secs(10));
    info!(" ---- done --- ");
    Ok(())
}    

Important Changes

Version 0.2

All version 0.2.* related information is available here Version 0.2.*.

Version 0.3.0-alpha.1

Breaking API changes from 0.2 This is the first async/await compatible version, it's not production ready yet, still work in progress. See examples in examples/ folder.

Version 0.3.0-alpha.3

This is the first async/await that works, but still missing features from version 0.2.

Version 0.3.0-alpha.4

Replaced std::sync::RwLock with futures::lock::Mutex for + Send + Sync capabilities.

Contact

For bug reports, patches, feature requests or other messages, please send a mail to michael@zulzi.com

License

This project is licensed under the MIT License.