r2r 0.9.5

Easy to use, runtime-agnostic, async rust bindings for ROS2.
Documentation 
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//
// This example is the same as action_client.rs but stripped of all (explicit) type information.
//
use futures::{executor::LocalPool, future::FutureExt, stream::StreamExt, task::LocalSpawnExt};

use std::sync::{Arc, Mutex};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let ctx = r2r::Context::create()?;
    let mut node = r2r::Node::create(ctx, "testnode", "")?;
    let client =
        node.create_action_client_untyped("/fibonacci", "example_interfaces/action/Fibonacci")?;
    let action_server_available = r2r::Node::is_available(&client)?;

    // signal that we are done
    let done = Arc::new(Mutex::new(false));

    let mut pool = LocalPool::new();
    let spawner = pool.spawner();

    let task_spawner = spawner.clone();
    let task_done = done.clone();
    spawner.spawn_local(async move {
        println!("waiting for action service...");
        action_server_available
            .await
            .expect("could not await action server");
        println!("action service available.");

        let goal = "{ \"order\": 5 }"; // Fibonacci::Goal { order: 5 };
        println!("sending goal: {}", goal);
        let (goal, result, feedback) = client
            .send_goal_request(serde_json::from_str(goal).expect("json malformed"))
            .expect("could not send goal request")
            .await
            .expect("goal rejected by server");

        println!("goal accepted: {}", goal.uuid);
        // process feedback stream in its own task
        let nested_goal = goal.clone();
        let nested_task_done = task_done.clone();
        task_spawner
            .spawn_local(feedback.for_each(move |msg| {
                let nested_task_done = nested_task_done.clone();
                let nested_goal = nested_goal.clone();
                async move {
                    if let Ok(msg) = msg {
                        let sequence = msg
                            .get("sequence")
                            .and_then(|s| s.as_array())
                            .expect("unexpected feedback msg");
                        println!("new feedback msg {} -- {:?}", msg, nested_goal.get_status());

                        // 50/50 that cancel the goal before it finishes.
                        if sequence.len() == 4 && rand::random::<bool>() {
                            nested_goal
                                .cancel()
                                .unwrap()
                                .map(|r| {
                                    println!("goal cancelled: {:?}", r);
                                    // we are done.
                                    *nested_task_done.lock().unwrap() = true;
                                })
                                .await;
                        }
                    }
                }
            }))
            .unwrap();

        // await result in this task
        match result.await {
            Ok((status, msg)) => {
                println!("got result {} with msg {:?}", status, msg);
                *task_done.lock().unwrap() = true;
            }
            Err(e) => println!("action failed: {:?}", e),
        }
    })?;

    loop {
        node.spin_once(std::time::Duration::from_millis(100));
        pool.run_until_stalled();
        if *done.lock().unwrap() {
            break;
        }
    }

    Ok(())
}