Hello Zenoh

Your first Zenoh program: a publisher and a subscriber in pure Rust.

Publisher

use zenoh::prelude::*;
 
#[tokio::main]
async fn main() {
    let session = zenoh::open(zenoh::config::default()).await.unwrap();
 
    loop {
        session
            .put("hello/zenoh", "Hello, Zenoh!")
            .await
            .unwrap();
        println!("Published");
        tokio::time::sleep(std::time::Duration::from_secs(1)).await;
    }
}

Subscriber

use zenoh::prelude::*;
 
#[tokio::main]
async fn main() {
    let session = zenoh::open(zenoh::config::default()).await.unwrap();
 
    let subscriber = session
        .declare_subscriber("hello/**")
        .await
        .unwrap();
 
    while let Ok(sample) = subscriber.recv_async().await {
        println!(
            "Received: {} = {:?}",
            sample.key_expr(),
            sample.payload()
        );
    }
}

Run It

In two separate terminals:

# Terminal 1 — subscriber
cargo run --example subscriber
 
# Terminal 2 — publisher
cargo run --example publisher

You should see the subscriber printing messages as the publisher sends them. No router is needed — the two peers discover each other via multicast scouting.

What Happened?

Both programs opened a Session (connection point to the Zenoh network)
The publisher used key expression hello/zenoh to label its data
The subscriber declared interest in hello/** — matching any key under hello/
Zenoh routed matching data automatically, without a central broker

Next: The Zenoh Router.