Add simple talk/listener tutorial, matching the official ROS 2 documentation #378 (#390)

* Added another tutorial to ros2 rust.

---------

Co-authored-by: GueLaKais <koroyeldores@gmail.com>
Co-authored-by: GueLaKais <koryeldiores@gmail.com>
Co-authored-by: Esteve Fernandez <esteve@apache.org>
Co-authored-by: Esteve Fernandez <33620+esteve@users.noreply.github.com>
Co-authored-by: Sam Privett <privett.sam@gmail.com>

Author: 5 people

rclrs/rust_pubsub/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "rust_pubsub"
+version = "0.1.0"
+edition = "2021"
+
+[[bin]]
+name="simple_publisher"
+path="src/simple_publisher.rs"
+
+[[bin]]
+name="simple_subscriber"
+path="src/simple_subscriber.rs"
+
+[dependencies]
+rclrs = "*"
+std_msgs = "*"

rclrs/rust_pubsub/package.xml

@@ -0,0 +1,14 @@
+<package format="3">
+  <name>rust_pubsub</name>
+  <version>0.0.0</version>
+  <description>TODO: Package description.</description>
+  <maintainer email="user@todo.todo">user</maintainer>
+  <license>TODO: License declaration.</license>
+
+  <depend>rclrs</depend>
+  <depend>std_msgs</depend>
+
+  <export>
+    <build_type>ament_cargo</build_type>
+  </export>
+</package>

rclrs/rust_pubsub/src/simple_publisher.rs

@@ -0,0 +1,36 @@
+use rclrs::{create_node, Context, Node, Publisher, RclrsError, QOS_PROFILE_DEFAULT};
+use std::{sync::Arc, thread, time::Duration};
+use std_msgs::msg::String as StringMsg;
+struct SimplePublisherNode {
+    node: Arc<Node>,
+    _publisher: Arc<Publisher<StringMsg>>,
+}
+impl SimplePublisherNode {
+    fn new(context: &Context) -> Result<Self, RclrsError> {
+        let node = create_node(context, "simple_publisher").unwrap();
+        let _publisher = node
+            .create_publisher("publish_hello", QOS_PROFILE_DEFAULT)
+            .unwrap();
+        Ok(Self { node, _publisher })
+    }
+
+    fn publish_data(&self, increment: i32) -> Result<i32, RclrsError> {
+        let msg: StringMsg = StringMsg {
+            data: format!("Hello World {}", increment),
+        };
+        self._publisher.publish(msg).unwrap();
+        Ok(increment + 1_i32)
+    }
+}
+
+fn main() -> Result<(), RclrsError> {
+    let context = Context::new(std::env::args()).unwrap();
+    let publisher = Arc::new(SimplePublisherNode::new(&context).unwrap());
+    let publisher_other_thread = Arc::clone(&publisher);
+    let mut count: i32 = 0;
+    thread::spawn(move || loop {
+        thread::sleep(Duration::from_millis(1000));
+        count = publisher_other_thread.publish_data(count).unwrap();
+    });
+    rclrs::spin(publisher.node.clone())
+}

rclrs/rust_pubsub/src/simple_subscriber.rs

@@ -0,0 +1,52 @@
+use rclrs::{create_node, Context, Node, RclrsError, Subscription, QOS_PROFILE_DEFAULT};
+use std::{
+    env,
+    sync::{Arc, Mutex},
+    thread,
+    time::Duration,
+};
+use std_msgs::msg::String as StringMsg;
+pub struct SimpleSubscriptionNode {
+    node: Arc<Node>,
+    _subscriber: Arc<Subscription<StringMsg>>,
+    data: Arc<Mutex<Option<StringMsg>>>,
+}
+impl SimpleSubscriptionNode {
+    fn new(context: &Context) -> Result<Self, RclrsError> {
+        let node = create_node(context, "simple_subscription").unwrap();
+        let data: Arc<Mutex<Option<StringMsg>>> = Arc::new(Mutex::new(None));
+        let data_mut: Arc<Mutex<Option<StringMsg>>> = Arc::clone(&data);
+        let _subscriber = node
+            .create_subscription::<StringMsg, _>(
+                "publish_hello",
+                QOS_PROFILE_DEFAULT,
+                move |msg: StringMsg| {
+                    *data_mut.lock().unwrap() = Some(msg);
+                },
+            )
+            .unwrap();
+        Ok(Self {
+            node,
+            _subscriber,
+            data,
+        })
+    }
+    fn data_callback(&self) -> Result<(), RclrsError> {
+        if let Some(data) = self.data.lock().unwrap().as_ref() {
+            println!("{}", data.data);
+        } else {
+            println!("No message available yet.");
+        }
+        Ok(())
+    }
+}
+fn main() -> Result<(), RclrsError> {
+    let context = Context::new(env::args()).unwrap();
+    let subscription = Arc::new(SimpleSubscriptionNode::new(&context).unwrap());
+    let subscription_other_thread = Arc::clone(&subscription);
+    thread::spawn(move || loop {
+        thread::sleep(Duration::from_millis(1000));
+        subscription_other_thread.data_callback().unwrap()
+    });
+    rclrs::spin(subscription.node.clone())
+}