From b7566ef5bc1712d4ee231169344028439357265a Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Thu, 7 Mar 2024 13:00:18 +0100
Subject: [PATCH 1/7] Implement message generation for ROS2 services in Rust
 API

---
 .../extensions/ros2-bridge/msg-gen/src/lib.rs | 12 ++++
 .../ros2-bridge/msg-gen/src/types/message.rs  | 71 ++++++++-----------
 .../ros2-bridge/msg-gen/src/types/package.rs  | 16 ++---
 .../ros2-bridge/msg-gen/src/types/service.rs  | 58 +++++++++++++++
 .../extensions/ros2-bridge/src/_core/mod.rs   |  5 +-
 .../ros2-bridge/src/_core/traits.rs           |  9 +--
 6 files changed, 111 insertions(+), 60 deletions(-)

diff --git a/libraries/extensions/ros2-bridge/msg-gen/src/lib.rs b/libraries/extensions/ros2-bridge/msg-gen/src/lib.rs
index 54e7155c..073f985c 100644
--- a/libraries/extensions/ros2-bridge/msg-gen/src/lib.rs
+++ b/libraries/extensions/ros2-bridge/msg-gen/src/lib.rs
@@ -25,6 +25,8 @@ where
     let mut message_struct_impls = Vec::new();
     let mut message_topic_defs = Vec::new();
     let mut message_topic_impls = Vec::new();
+    let mut service_defs = Vec::new();
+    let mut service_impls = Vec::new();
     let mut aliases = Vec::new();
     for package in &packages {
         for message in &package.messages {
@@ -37,6 +39,13 @@ where
                 message_topic_impls.push(topic_impl);
             }
         }
+
+        for service in &package.services {
+            let (def, imp) = service.struct_token_stream(&package.name, create_cxx_bridge);
+            service_defs.push(def);
+            service_impls.push(imp);
+        }
+
         aliases.push(package.aliases_token_stream());
     }
 
@@ -212,6 +221,7 @@ where
             }
 
             #(#shared_type_defs)*
+            #(#service_defs)*
         }
 
 
@@ -227,6 +237,8 @@ where
         #(#message_topic_impls)*
 
 
+        #(#service_impls)*
+
         #(#aliases)*
     }
 }
diff --git a/libraries/extensions/ros2-bridge/msg-gen/src/types/message.rs b/libraries/extensions/ros2-bridge/msg-gen/src/types/message.rs
index 01bc8327..f3e1ea09 100644
--- a/libraries/extensions/ros2-bridge/msg-gen/src/types/message.rs
+++ b/libraries/extensions/ros2-bridge/msg-gen/src/types/message.rs
@@ -180,44 +180,45 @@ impl Message {
         };
 
         if self.members.is_empty() {
-            (quote! {}, quote! {})
-        } else {
-            let def = quote! {
-                #[allow(non_camel_case_types)]
-                #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
-                #attributes
-                pub struct #struct_raw_name {
-                    #(#rust_type_def_inner)*
-                }
+            (quote! {}, quote! {});
+        }
+        let def = quote! {
+            #[allow(non_camel_case_types)]
+            #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+            #attributes
+            pub struct #struct_raw_name {
+                #(#rust_type_def_inner)*
+            }
 
-                #cxx_consts
-            };
-            let impls = quote! {
-                impl ffi::#struct_raw_name {
-                    #(#constants_def_inner)*
+            #cxx_consts
+        };
+        let impls = quote! {
+            impl ffi::#struct_raw_name {
+                #(#constants_def_inner)*
 
-                }
+            }
 
-                impl crate::_core::InternalDefault for ffi::#struct_raw_name {
-                    fn _default() -> Self {
-                        Self {
-                            #(#rust_type_default_inner)*
-                        }
+            impl crate::_core::InternalDefault for ffi::#struct_raw_name {
+                fn _default() -> Self {
+                    Self {
+                        #(#rust_type_default_inner)*
                     }
                 }
+            }
 
-                impl std::default::Default for ffi::#struct_raw_name {
-                    #[inline]
-                    fn default() -> Self {
-                        crate::_core::InternalDefault::_default()
-                    }
+            impl std::default::Default for ffi::#struct_raw_name {
+                #[inline]
+                fn default() -> Self {
+                    crate::_core::InternalDefault::_default()
                 }
+            }
 
-                #(#cxx_const_impl_inner)*
-            };
+            impl ros2_client::Message for ffi::#struct_raw_name {}
 
-            (def, impls)
-        }
+            #(#cxx_const_impl_inner)*
+        };
+
+        (def, impls)
     }
 
     pub fn topic_def(&self, package_name: &str) -> (impl ToTokens, impl ToTokens) {
@@ -372,18 +373,6 @@ impl Message {
         }
     }
 
-    pub fn token_stream_with_mod(&self, gen_cxx_bridge: bool) -> impl ToTokens {
-        let mod_name = format_ident!("_{}", self.name.to_snake_case());
-        let inner = self.token_stream_args(gen_cxx_bridge);
-
-        quote! {
-            pub use #mod_name::*;
-            mod #mod_name {
-                #inner
-            }
-        }
-    }
-
     pub fn token_stream(&self) -> impl ToTokens {
         self.token_stream_args(false)
     }
diff --git a/libraries/extensions/ros2-bridge/msg-gen/src/types/package.rs b/libraries/extensions/ros2-bridge/msg-gen/src/types/package.rs
index ab0ccb3c..b42901ee 100644
--- a/libraries/extensions/ros2-bridge/msg-gen/src/types/package.rs
+++ b/libraries/extensions/ros2-bridge/msg-gen/src/types/package.rs
@@ -65,20 +65,20 @@ impl Package {
         }
     }
 
-    fn messages_block(&self, gen_cxx_bridge: bool) -> impl ToTokens {
-        if self.messages.is_empty() {
+    fn service_aliases(&self, package_name: &Ident) -> impl ToTokens {
+        if self.services.is_empty() {
             quote! {
                 // empty msg
             }
         } else {
             let items = self
-                .messages
+                .services
                 .iter()
-                .map(|v| v.token_stream_with_mod(gen_cxx_bridge));
+                .map(|v| v.alias_token_stream(package_name));
             quote! {
-                pub mod msg {
+                pub mod service {
                     #(#items)*
-                }  // msg
+                }
             }
         }
     }
@@ -116,23 +116,23 @@ impl Package {
     pub fn aliases_token_stream(&self) -> impl ToTokens {
         let package_name = Ident::new(&self.name, Span::call_site());
         let aliases = self.message_aliases(&package_name);
+        let service_aliases = self.service_aliases(&package_name);
 
         quote! {
             pub mod #package_name {
                 #aliases
+                #service_aliases
             }
         }
     }
 
     pub fn token_stream(&self, gen_cxx_bridge: bool) -> impl ToTokens {
         let name = Ident::new(&self.name, Span::call_site());
-        let messages_block = self.messages_block(gen_cxx_bridge);
         let services_block = self.services_block();
         let actions_block = self.actions_block();
 
         quote! {
             pub mod #name {
-                #messages_block
                 #services_block
                 #actions_block
             }
diff --git a/libraries/extensions/ros2-bridge/msg-gen/src/types/service.rs b/libraries/extensions/ros2-bridge/msg-gen/src/types/service.rs
index bc3b8727..95e7fb71 100644
--- a/libraries/extensions/ros2-bridge/msg-gen/src/types/service.rs
+++ b/libraries/extensions/ros2-bridge/msg-gen/src/types/service.rs
@@ -1,5 +1,6 @@
 use heck::SnakeCase;
 use quote::{format_ident, quote, ToTokens};
+use syn::Ident;
 
 use super::Message;
 
@@ -17,6 +18,63 @@ pub struct Service {
 }
 
 impl Service {
+    pub fn struct_token_stream(
+        &self,
+        package_name: &str,
+        gen_cxx_bridge: bool,
+    ) -> (impl ToTokens, impl ToTokens) {
+        let (request_def, request_impl) = self
+            .request
+            .struct_token_stream(package_name, gen_cxx_bridge);
+        let (response_def, response_impl) = self
+            .response
+            .struct_token_stream(package_name, gen_cxx_bridge);
+
+        let def = quote! {
+            #request_def
+            #response_def
+        };
+
+        let impls = quote! {
+            #request_impl
+            #response_impl
+        };
+
+        (def, impls)
+    }
+
+    pub fn alias_token_stream(&self, package_name: &Ident) -> impl ToTokens {
+        let srv_type = format_ident!("{}", self.name);
+        let req_type = format_ident!("{}_Request", self.name);
+        let req_type_raw = format_ident!("{package_name}__{}", req_type);
+        let res_type = format_ident!("{}_Response", self.name);
+        let res_type_raw = format_ident!("{package_name}__{}", res_type);
+
+        let request_type_name = req_type.to_string();
+        let response_type_name = res_type.to_string();
+
+        quote! {
+            #[allow(non_camel_case_types)]
+            #[derive(std::fmt::Debug)]
+            pub struct #srv_type;
+
+            impl ros2_client::Service for #srv_type {
+                type Request = #req_type;
+                type Response = #res_type;
+
+                fn request_type_name(&self) -> &str {
+                    #request_type_name
+                }
+                fn response_type_name(&self) -> &str {
+                    #response_type_name
+                }
+            }
+
+            pub use super::super::ffi::#req_type_raw as #req_type;
+            pub use super::super::ffi::#res_type_raw as #res_type;
+        }
+    }
+
     pub fn token_stream_with_mod(&self) -> impl ToTokens {
         let mod_name = format_ident!("_{}", self.name.to_snake_case());
         let inner = self.token_stream();
diff --git a/libraries/extensions/ros2-bridge/src/_core/mod.rs b/libraries/extensions/ros2-bridge/src/_core/mod.rs
index 167cd9e4..31b88dce 100644
--- a/libraries/extensions/ros2-bridge/src/_core/mod.rs
+++ b/libraries/extensions/ros2-bridge/src/_core/mod.rs
@@ -6,7 +6,4 @@ pub mod traits;
 
 pub use sequence::{FFISeq, OwnedFFISeq, RefFFISeq};
 pub use string::{FFIString, FFIWString, OwnedFFIString, OwnedFFIWString};
-pub use traits::{ActionT, FFIFromRust, FFIToRust, InternalDefault, MessageT, ServiceT};
-
-pub type ServiceRequestRaw<Srv> = <<Srv as ServiceT>::Request as MessageT>::Raw;
-pub type ServiceResponseRaw<Srv> = <<Srv as ServiceT>::Response as MessageT>::Raw;
+pub use traits::{ActionT, FFIFromRust, FFIToRust, InternalDefault, MessageT};
diff --git a/libraries/extensions/ros2-bridge/src/_core/traits.rs b/libraries/extensions/ros2-bridge/src/_core/traits.rs
index a40f10c4..709f3407 100644
--- a/libraries/extensions/ros2-bridge/src/_core/traits.rs
+++ b/libraries/extensions/ros2-bridge/src/_core/traits.rs
@@ -16,17 +16,12 @@ pub trait MessageT: Default + Send + Sync {
     }
 }
 
-pub trait ServiceT: Send {
-    type Request: MessageT;
-    type Response: MessageT;
-}
-
 pub trait ActionT: Send {
     type Goal: MessageT;
     type Result: MessageT;
     type Feedback: MessageT;
-    type SendGoal: ServiceT;
-    type GetResult: ServiceT;
+    type SendGoal;
+    type GetResult;
     type FeedbackMessage: MessageT;
 }
 

From 1a925175c5b78c60b64899ae175639d3bfd32384 Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Tue, 19 Mar 2024 19:14:00 +0100
Subject: [PATCH 2/7] Adjust names of generated service structs slightly

---
 .../extensions/ros2-bridge/msg-gen/src/types/service.rs  | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/libraries/extensions/ros2-bridge/msg-gen/src/types/service.rs b/libraries/extensions/ros2-bridge/msg-gen/src/types/service.rs
index 95e7fb71..03c9183a 100644
--- a/libraries/extensions/ros2-bridge/msg-gen/src/types/service.rs
+++ b/libraries/extensions/ros2-bridge/msg-gen/src/types/service.rs
@@ -45,10 +45,11 @@ impl Service {
 
     pub fn alias_token_stream(&self, package_name: &Ident) -> impl ToTokens {
         let srv_type = format_ident!("{}", self.name);
-        let req_type = format_ident!("{}_Request", self.name);
-        let req_type_raw = format_ident!("{package_name}__{}", req_type);
-        let res_type = format_ident!("{}_Response", self.name);
-        let res_type_raw = format_ident!("{package_name}__{}", res_type);
+        let req_type_raw = format_ident!("{package_name}__{}_Request", self.name);
+        let res_type_raw = format_ident!("{package_name}__{}_Response", self.name);
+
+        let req_type = format_ident!("{}Request", self.name);
+        let res_type = format_ident!("{}Response", self.name);
 
         let request_type_name = req_type.to_string();
         let response_type_name = res_type.to_string();

From 4a0971a1eb10831d5018a65b93ae3953e9f6ed90 Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Tue, 19 Mar 2024 19:16:36 +0100
Subject: [PATCH 3/7] Update `rust-ros2-dataflow` example with ROS2 service
 call

Call the `add_two_ints` service and check the result. This requires that the following command is executed in a separate terminal before:

`ros2 run examples_rclcpp_minimal_service service_main`
---
 Cargo.lock                                   |  6 +-
 examples/rust-ros2-dataflow/README.md        |  5 +-
 examples/rust-ros2-dataflow/dataflow.yml     |  1 +
 examples/rust-ros2-dataflow/node/Cargo.toml  |  3 +-
 examples/rust-ros2-dataflow/node/src/main.rs | 90 +++++++++++++++++++-
 5 files changed, 100 insertions(+), 5 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 19f5f4d7..9b6e26a8 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2097,6 +2097,7 @@ dependencies = [
  "futures-core",
  "futures-task",
  "futures-util",
+ "num_cpus",
 ]
 
 [[package]]
@@ -2158,9 +2159,9 @@ checksum = "76d3d132be6c0e6aa1534069c705a74a5997a356c0dc2f86a47765e5617c5b65"
 
 [[package]]
 name = "futures-timer"
-version = "3.0.2"
+version = "3.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e64b03909df88034c26dc1547e8970b91f98bdb65165d6a4e9110d94263dbb2c"
+checksum = "f288b0a4f20f9a56b5d1da57e2227c661b7b16168e2f72365f57b63326e29b24"
 
 [[package]]
 name = "futures-util"
@@ -4662,6 +4663,7 @@ dependencies = [
  "dora-ros2-bridge",
  "eyre",
  "futures",
+ "futures-timer",
  "rand",
  "serde_json",
  "tokio",
diff --git a/examples/rust-ros2-dataflow/README.md b/examples/rust-ros2-dataflow/README.md
index 6c8445e9..c30e52e6 100644
--- a/examples/rust-ros2-dataflow/README.md
+++ b/examples/rust-ros2-dataflow/README.md
@@ -11,11 +11,14 @@ This examples requires a sourced ROS2 installation.
 - Follow tasks 1 and 2 of the [ROS2 turtlesim tutorial](https://docs.ros.org/en/iron/Tutorials/Beginner-CLI-Tools/Introducing-Turtlesim/Introducing-Turtlesim.html#id3)
   - Install the turtlesim package
   - Start the turtlesim node through `ros2 run turtlesim turtlesim_node`
+- In a separate terminal, start the `/add_two_ints` service: `ros2 run examples_rclcpp_minimal_service service_main`
 
 ## Running
 
-After sourcing the ROS2 installation and starting the `turtlesim` node, you can run this example to move the turtle in random directions:
+After sourcing the ROS2 installation and starting both the `turtlesim` node and the `/add_two_ints` service, you can run this example to move the turtle in random directions:
 
 ```
 cargo run --example rust-ros2-dataflow --features ros2-examples
 ```
+
+You should see a few random requests in the terminal where you started the `examples_rclcpp_minimal_service`.
diff --git a/examples/rust-ros2-dataflow/dataflow.yml b/examples/rust-ros2-dataflow/dataflow.yml
index 83583f75..080f1f5d 100644
--- a/examples/rust-ros2-dataflow/dataflow.yml
+++ b/examples/rust-ros2-dataflow/dataflow.yml
@@ -5,5 +5,6 @@ nodes:
       source: ../../target/debug/rust-ros2-dataflow-example-node
       inputs:
         tick: dora/timer/millis/500
+        service_timer: dora/timer/secs/1
       outputs:
         - pose
diff --git a/examples/rust-ros2-dataflow/node/Cargo.toml b/examples/rust-ros2-dataflow/node/Cargo.toml
index 90d3efa6..c984455e 100644
--- a/examples/rust-ros2-dataflow/node/Cargo.toml
+++ b/examples/rust-ros2-dataflow/node/Cargo.toml
@@ -16,7 +16,8 @@ required-features = ["ros2"]
 [dependencies]
 dora-node-api = { workspace = true, features = ["tracing"] }
 eyre = "0.6.8"
-futures = "0.3.21"
+futures = { version = "0.3.21", features = ["thread-pool"] }
+futures-timer = "3.0.3"
 rand = "0.8.5"
 tokio = { version = "1.24.2", features = ["rt", "macros"] }
 dora-ros2-bridge = { workspace = true }
diff --git a/examples/rust-ros2-dataflow/node/src/main.rs b/examples/rust-ros2-dataflow/node/src/main.rs
index 6d20472f..454b51d9 100644
--- a/examples/rust-ros2-dataflow/node/src/main.rs
+++ b/examples/rust-ros2-dataflow/node/src/main.rs
@@ -1,3 +1,5 @@
+use std::time::Duration;
+
 use dora_node_api::{
     self,
     dora_core::config::DataId,
@@ -6,19 +8,70 @@ use dora_node_api::{
 };
 use dora_ros2_bridge::{
     messages::{
+        example_interfaces::service::{AddTwoInts, AddTwoIntsRequest},
         geometry_msgs::msg::{Twist, Vector3},
-        turtlesim::msg::Pose,
+        turtlesim::{
+            msg::Pose,
+            service::{Spawn, SpawnRequest},
+        },
     },
     ros2_client::{self, ros2, NodeOptions},
     rustdds::{self, policy},
 };
 use eyre::{eyre, Context};
+use futures::task::SpawnExt;
 
 fn main() -> eyre::Result<()> {
     let mut ros_node = init_ros_node()?;
     let turtle_vel_publisher = create_vel_publisher(&mut ros_node)?;
     let turtle_pose_reader = create_pose_reader(&mut ros_node)?;
 
+    let service_qos = {
+        rustdds::QosPolicyBuilder::new()
+            .reliability(policy::Reliability::Reliable {
+                max_blocking_time: rustdds::Duration::from_millis(100),
+            })
+            .history(policy::History::KeepLast { depth: 1 })
+            .build()
+    };
+    let add_client = ros_node.create_client::<AddTwoInts>(
+        ros2_client::ServiceMapping::Enhanced,
+        &ros2_client::Name::new("/", "add_two_ints").unwrap(),
+        &ros2_client::ServiceTypeName::new("example_interfaces", "AddTwoInts"),
+        service_qos.clone(),
+        service_qos.clone(),
+    )?;
+
+    let pool = futures::executor::ThreadPool::new()?;
+
+    let spinner = ros_node.spinner();
+    pool.spawn(async {
+        if let Err(err) = spinner.spin().await {
+            eprintln!("ros2 spinner failed: {err:?}");
+        }
+    })
+    .context("failed to spawn ros2 spinner")?;
+
+    println!("wait for add_two_ints service");
+    let service_ready = async {
+        for _ in 0..10 {
+            let ready = add_client.wait_for_service(&ros_node);
+            futures::pin_mut!(ready);
+            let timeout = futures_timer::Delay::new(Duration::from_secs(2));
+            match futures::future::select(ready, timeout).await {
+                futures::future::Either::Left(((), _)) => {
+                    println!("add_two_ints service is ready");
+                    return Ok(());
+                }
+                futures::future::Either::Right(_) => {
+                    println!("timeout while waiting for add_two_ints service, retrying");
+                }
+            }
+        }
+        eyre::bail!("add_to_ints service not available");
+    };
+    futures::executor::block_on(service_ready)?;
+
     let output = DataId::from("pose".to_owned());
 
     let (mut node, dora_events) = DoraNode::init_from_env()?;
@@ -53,6 +106,16 @@ fn main() -> eyre::Result<()> {
                         println!("tick {i}, sending {direction:?}");
                         turtle_vel_publisher.publish(direction).unwrap();
                     }
+                    "service_timer" => {
+                        let a = rand::random();
+                        let b = rand::random();
+                        let service_result = add_two_ints_request(&add_client, a, b);
+                        let sum = futures::executor::block_on(service_result)
+                            .context("failed to send service request")?;
+                        if sum != a.wrapping_add(b) {
+                            eyre::bail!("unexpected addition result: expected {}, got {sum}", a + b)
+                        }
+                    }
                     other => eprintln!("Ignoring unexpected input `{other}`"),
                 },
                 Event::Stop => println!("Received manual stop"),
@@ -76,6 +139,31 @@ fn main() -> eyre::Result<()> {
     Ok(())
 }
 
+async fn add_two_ints_request(
+    add_client: &ros2_client::Client<AddTwoInts>,
+    a: i64,
+    b: i64,
+) -> eyre::Result<i64> {
+    let request = AddTwoIntsRequest { a, b };
+    println!("sending add request {request:?}");
+    let request_id = add_client.async_send_request(request.clone()).await?;
+    println!("{request_id:?}");
+
+    let response = add_client.async_receive_response(request_id);
+    futures::pin_mut!(response);
+    let timeout = futures_timer::Delay::new(Duration::from_secs(5));
+    match futures::future::select(response, timeout).await {
+        futures::future::Either::Left((Ok(response), _)) => {
+            println!("received response: {response:?}");
+            Ok(response.sum)
+        }
+        futures::future::Either::Left((Err(err), _)) => eyre::bail!(err),
+        futures::future::Either::Right(_) => {
+            eyre::bail!("timeout while waiting for response");
+        }
+    }
+}
+
 fn init_ros_node() -> eyre::Result<ros2_client::Node> {
     let ros_context = ros2_client::Context::new().unwrap();
 

From 70498e3292e2d73bdbd22b8579e91a6465f2e12c Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Tue, 19 Mar 2024 19:26:40 +0100
Subject: [PATCH 4/7] Minor improvements

---
 examples/rust-ros2-dataflow/node/src/main.rs | 27 ++++++++++----------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/examples/rust-ros2-dataflow/node/src/main.rs b/examples/rust-ros2-dataflow/node/src/main.rs
index 454b51d9..90775296 100644
--- a/examples/rust-ros2-dataflow/node/src/main.rs
+++ b/examples/rust-ros2-dataflow/node/src/main.rs
@@ -10,10 +10,7 @@ use dora_ros2_bridge::{
     messages::{
         example_interfaces::service::{AddTwoInts, AddTwoIntsRequest},
         geometry_msgs::msg::{Twist, Vector3},
-        turtlesim::{
-            msg::Pose,
-            service::{Spawn, SpawnRequest},
-        },
+        turtlesim::msg::Pose,
     },
     ros2_client::{self, ros2, NodeOptions},
     rustdds::{self, policy},
@@ -26,6 +23,17 @@ fn main() -> eyre::Result<()> {
     let turtle_vel_publisher = create_vel_publisher(&mut ros_node)?;
     let turtle_pose_reader = create_pose_reader(&mut ros_node)?;
 
+    // spawn a background spinner task that is handles service discovery (and other things)
+    let pool = futures::executor::ThreadPool::new()?;
+    let spinner = ros_node.spinner();
+    pool.spawn(async {
+        if let Err(err) = spinner.spin().await {
+            eprintln!("ros2 spinner failed: {err:?}");
+        }
+    })
+    .context("failed to spawn ros2 spinner")?;
+
+    // create an example service client
     let service_qos = {
         rustdds::QosPolicyBuilder::new()
             .reliability(policy::Reliability::Reliable {
@@ -42,16 +50,7 @@ fn main() -> eyre::Result<()> {
         service_qos.clone(),
     )?;
 
-    let pool = futures::executor::ThreadPool::new()?;
-
-    let spinner = ros_node.spinner();
-    pool.spawn(async {
-        if let Err(err) = spinner.spin().await {
-            eprintln!("ros2 spinner failed: {err:?}");
-        }
-    })
-    .context("failed to spawn ros2 spinner")?;
-
+    // wait until the service server is ready
     println!("wait for add_two_ints service");
     let service_ready = async {
         for _ in 0..10 {

From 3a72b2765b5086f81ee56198f6735d77c9ad40eb Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Tue, 19 Mar 2024 19:36:01 +0100
Subject: [PATCH 5/7] CI: Start `examples_rclcpp_minimal_service` service for
 `rust-ros2-dataflow` example

---
 .github/workflows/ci.yml                     | 1 +
 examples/rust-ros2-dataflow/node/src/main.rs | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 70234f29..17b3e994 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -174,6 +174,7 @@ jobs:
           QT_QPA_PLATFORM: offscreen
         run: |
           source /opt/ros/humble/setup.bash && ros2 run turtlesim turtlesim_node &
+          source /opt/ros/humble/setup.bash && ros2 run examples_rclcpp_minimal_service service_main &
           cargo run --example rust-ros2-dataflow --features="ros2-examples"
       - uses: actions/setup-python@v2
         if: runner.os != 'Windows'
diff --git a/examples/rust-ros2-dataflow/node/src/main.rs b/examples/rust-ros2-dataflow/node/src/main.rs
index 90775296..32ac8cf4 100644
--- a/examples/rust-ros2-dataflow/node/src/main.rs
+++ b/examples/rust-ros2-dataflow/node/src/main.rs
@@ -67,7 +67,7 @@ fn main() -> eyre::Result<()> {
                 }
             }
         }
-        eyre::bail!("add_to_ints service not available");
+        eyre::bail!("add_two_ints service not available");
     };
     futures::executor::block_on(service_ready)?;
 

From 23a05f1f32101a6c8d85cfb139bf3bb2c58b2381 Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Wed, 20 Mar 2024 13:27:16 +0100
Subject: [PATCH 6/7] Add dummy field to empty structs to make them compatible
 with C++ bridge

---
 .../ros2-bridge/msg-gen/src/types/message.rs  | 48 ++++++++++++++-----
 1 file changed, 35 insertions(+), 13 deletions(-)

diff --git a/libraries/extensions/ros2-bridge/msg-gen/src/types/message.rs b/libraries/extensions/ros2-bridge/msg-gen/src/types/message.rs
index f3e1ea09..6e06b0db 100644
--- a/libraries/extensions/ros2-bridge/msg-gen/src/types/message.rs
+++ b/libraries/extensions/ros2-bridge/msg-gen/src/types/message.rs
@@ -179,18 +179,42 @@ impl Message {
             (quote! {}, quote! {})
         };
 
-        if self.members.is_empty() {
-            (quote! {}, quote! {});
-        }
-        let def = quote! {
-            #[allow(non_camel_case_types)]
-            #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
-            #attributes
-            pub struct #struct_raw_name {
-                #(#rust_type_def_inner)*
+        let def = if self.members.is_empty() {
+            quote! {
+                #[allow(non_camel_case_types)]
+                #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+                #attributes
+                pub struct #struct_raw_name {
+                    #[serde(skip)]
+                    pub(super) _dummy: u8,
+                }
+
+                #cxx_consts
             }
+        } else {
+            quote! {
+                #[allow(non_camel_case_types)]
+                #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+                #attributes
+                pub struct #struct_raw_name {
+                    #(#rust_type_def_inner)*
+                }
 
-            #cxx_consts
+                #cxx_consts
+            }
+        };
+        let default = if self.members.is_empty() {
+            quote! {
+                Self {
+                    _dummy: 0,
+                }
+            }
+        } else {
+            quote! {
+                Self {
+                    #(#rust_type_default_inner)*
+                }
+            }
         };
         let impls = quote! {
             impl ffi::#struct_raw_name {
@@ -200,9 +224,7 @@ impl Message {
 
             impl crate::_core::InternalDefault for ffi::#struct_raw_name {
                 fn _default() -> Self {
-                    Self {
-                        #(#rust_type_default_inner)*
-                    }
+                    #default
                 }
             }
 

From 3a249642ab05230f68ad2b1ad476a32eb2774ad0 Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Wed, 20 Mar 2024 14:14:54 +0100
Subject: [PATCH 7/7] Fix unresolved crate errors in generated code for C++ API

---
 apis/c++/node/src/lib.rs                               |  2 +-
 .../ros2-bridge/msg-gen/src/types/message.rs           | 10 +++++-----
 .../ros2-bridge/msg-gen/src/types/service.rs           |  2 +-
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/apis/c++/node/src/lib.rs b/apis/c++/node/src/lib.rs
index 5c5659a2..e3476de8 100644
--- a/apis/c++/node/src/lib.rs
+++ b/apis/c++/node/src/lib.rs
@@ -9,7 +9,7 @@ use dora_node_api::{
 use eyre::bail;
 
 #[cfg(feature = "ros2-bridge")]
-use dora_ros2_bridge::_core;
+use dora_ros2_bridge::{_core, ros2_client};
 use futures_lite::{stream, Stream, StreamExt};
 
 #[cxx::bridge]
diff --git a/libraries/extensions/ros2-bridge/msg-gen/src/types/message.rs b/libraries/extensions/ros2-bridge/msg-gen/src/types/message.rs
index 6e06b0db..157d88ce 100644
--- a/libraries/extensions/ros2-bridge/msg-gen/src/types/message.rs
+++ b/libraries/extensions/ros2-bridge/msg-gen/src/types/message.rs
@@ -235,7 +235,7 @@ impl Message {
                 }
             }
 
-            impl ros2_client::Message for ffi::#struct_raw_name {}
+            impl crate::ros2_client::Message for ffi::#struct_raw_name {}
 
             #(#cxx_const_impl_inner)*
         };
@@ -312,8 +312,8 @@ impl Message {
             impl Ros2Node {
                 #[allow(non_snake_case)]
                 pub fn #create_topic(&self, name_space: &str, base_name: &str, qos: ffi::Ros2QosPolicies) -> eyre::Result<Box<#topic_name>> {
-                    let name = ros2_client::Name::new(name_space, base_name).map_err(|e| eyre::eyre!(e))?;
-                    let type_name = ros2_client::MessageTypeName::new(#package_name, #self_name);
+                    let name = crate::ros2_client::Name::new(name_space, base_name).map_err(|e| eyre::eyre!(e))?;
+                    let type_name = crate::ros2_client::MessageTypeName::new(#package_name, #self_name);
                     let topic = self.0.create_topic(&name, type_name, &qos.into())?;
                     Ok(Box::new(#topic_name(topic)))
                 }
@@ -339,7 +339,7 @@ impl Message {
             }
 
             #[allow(non_camel_case_types)]
-            pub struct #publisher_name(ros2_client::Publisher<ffi::#struct_raw_name>);
+            pub struct #publisher_name(crate::ros2_client::Publisher<ffi::#struct_raw_name>);
 
             impl #publisher_name {
                 #[allow(non_snake_case)]
@@ -368,7 +368,7 @@ impl Message {
 
                     match (*event.event).0 {
                         Some(crate::MergedEvent::External(event)) if event.id == self.id  => {
-                            let result = event.event.downcast::<rustdds::dds::result::ReadResult<(ffi::#struct_raw_name, ros2_client::MessageInfo)>>()
+                            let result = event.event.downcast::<rustdds::dds::result::ReadResult<(ffi::#struct_raw_name, crate::ros2_client::MessageInfo)>>()
                                 .map_err(|_| eyre::eyre!("downcast to {} failed", #struct_raw_name_str))?;
 
                             let (data, _info) = result.with_context(|| format!("failed to receive {} event", #subscription_name_str))?;
diff --git a/libraries/extensions/ros2-bridge/msg-gen/src/types/service.rs b/libraries/extensions/ros2-bridge/msg-gen/src/types/service.rs
index 03c9183a..f86b4080 100644
--- a/libraries/extensions/ros2-bridge/msg-gen/src/types/service.rs
+++ b/libraries/extensions/ros2-bridge/msg-gen/src/types/service.rs
@@ -59,7 +59,7 @@ impl Service {
             #[derive(std::fmt::Debug)]
             pub struct #srv_type;
 
-            impl ros2_client::Service for #srv_type {
+            impl crate::ros2_client::Service for #srv_type {
                 type Request = #req_type;
                 type Response = #res_type;