Added support for clients and services (#146)

* Added support for clients and services

Author: esteve

rclrs/minimal_client_service/Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "examples_rclrs_minimal_client_service"
+version = "0.2.0"
+authors = ["Esteve Fernandez <esteve@apache.org>"]
+edition = "2021"
+
+[[bin]]
+name = "minimal_client"
+path = "src/minimal_client.rs"
+
+[[bin]]
+name = "minimal_client_async"
+path = "src/minimal_client_async.rs"
+
+[[bin]]
+name = "minimal_service"
+path = "src/minimal_service.rs"
+
+[dependencies]
+anyhow = {version = "1", features = ["backtrace"]}
+tokio = { version = "1", features = ["macros", "rt", "rt-multi-thread", "time"] }
+
+[dependencies.rclrs]
+version = "*"
+
+[dependencies.rosidl_runtime_rs]
+version = "*"
+
+[dependencies.example_interfaces]
+version = "*"

rclrs/minimal_client_service/package.xml

@@ -0,0 +1,23 @@
+<?xml version="1.0"?>
+<?xml-model
+   href="http://download.ros.org/schema/package_format3.xsd"
+   schematypens="http://www.w3.org/2001/XMLSchema"?>
+<package format="3">
+  <name>examples_rclrs_minimal_client_service</name>
+  <version>0.2.0</version>
+  <description>Package containing an example of the client-service mechanism in rclrs.</description>
+  <maintainer email="esteve@apache.org">Esteve Fernandez</maintainer>
+  <license>Apache License 2.0</license>
+
+  <build_depend>example_interfaces</build_depend>
+  <build_depend>rclrs</build_depend>
+  <build_depend>rosidl_runtime_rs</build_depend>
+
+  <exec_depend>example_interfaces</exec_depend>
+  <exec_depend>rclrs</exec_depend>
+  <exec_depend>rosidl_runtime_rs</exec_depend>
+
+  <export>
+    <build_type>ament_cargo</build_type>
+  </export>
+</package>

rclrs/minimal_client_service/src/minimal_client.rs

@@ -0,0 +1,31 @@
+use anyhow::{Error, Result};
+use std::env;
+
+fn main() -> Result<(), Error> {
+    let context = rclrs::Context::new(env::args())?;
+
+    let mut node = context.create_node("minimal_client")?;
+
+    let client = node.create_client::<example_interfaces::srv::AddTwoInts>("add_two_ints")?;
+
+    let request = example_interfaces::srv::AddTwoInts_Request { a: 41, b: 1 };
+
+    println!("Starting client");
+
+    std::thread::sleep(std::time::Duration::from_millis(500));
+
+    client.async_send_request_with_callback(
+        &request,
+        move |response: example_interfaces::srv::AddTwoInts_Response| {
+            println!(
+                "Result of {} + {} is: {}",
+                request.a, request.b, response.sum
+            );
+        },
+    )?;
+
+    std::thread::sleep(std::time::Duration::from_millis(500));
+
+    println!("Waiting for response");
+    rclrs::spin(&node).map_err(|err| err.into())
+}

rclrs/minimal_client_service/src/minimal_client_async.rs

@@ -0,0 +1,32 @@
+use anyhow::{Error, Result};
+use std::env;
+
+#[tokio::main]
+async fn main() -> Result<(), Error> {
+    let context = rclrs::Context::new(env::args())?;
+
+    let mut node = context.create_node("minimal_client")?;
+
+    let client = node.create_client::<example_interfaces::srv::AddTwoInts>("add_two_ints")?;
+
+    println!("Starting client");
+
+    std::thread::sleep(std::time::Duration::from_millis(500));
+
+    let request = example_interfaces::srv::AddTwoInts_Request { a: 41, b: 1 };
+
+    let future = client.call_async(&request);
+
+    println!("Waiting for response");
+
+    let rclrs_spin = tokio::task::spawn_blocking(move || rclrs::spin(&node));
+
+    let response = future.await?;
+    println!(
+        "Result of {} + {} is: {}",
+        request.a, request.b, response.sum
+    );
+
+    rclrs_spin.await.ok();
+    Ok(())
+}

rclrs/minimal_client_service/src/minimal_service.rs

@@ -0,0 +1,24 @@
+use anyhow::{Error, Result};
+use std::env;
+
+fn handle_service(
+    _request_header: &rclrs::rmw_request_id_t,
+    request: example_interfaces::srv::AddTwoInts_Request,
+) -> example_interfaces::srv::AddTwoInts_Response {
+    println!("request: {} + {}", request.a, request.b);
+    example_interfaces::srv::AddTwoInts_Response {
+        sum: request.a + request.b,
+    }
+}
+
+fn main() -> Result<(), Error> {
+    let context = rclrs::Context::new(env::args())?;
+
+    let mut node = context.create_node("minimal_service")?;
+
+    let _server = node
+        .create_service::<example_interfaces::srv::AddTwoInts, _>("add_two_ints", handle_service)?;
+
+    println!("Starting server");
+    rclrs::spin(&node).map_err(|err| err.into())
+}

rclrs/minimal_pub_sub/src/minimal_subscriber.rs

@@ -1,6 +1,5 @@
-use std::env;
-
 use anyhow::{Error, Result};
+use std::env;
 
 fn main() -> Result<(), Error> {
     let context = rclrs::Context::new(env::args())?;