ros2_tracing/tracetools_test/src/test_service_pong.cpp

#include <memory>

#include "rclcpp/rclcpp.hpp"
#include "std_srvs/srv/empty.hpp"

class PongNode : public rclcpp::Node
{
public:
  explicit PongNode(rclcpp::NodeOptions options)
  : Node("pong_node", options)
  {
    srv_ = this->create_service<std_srvs::srv::Empty>(
      "ping",
      std::bind(
        &PongNode::service_callback,
        this,
        std::placeholders::_1,
        std::placeholders::_2,
        std::placeholders::_3));
    client_ = this->create_client<std_srvs::srv::Empty>("pong");
  }

private:
  void service_callback(
    const std::shared_ptr<rmw_request_id_t> request_header,
    const std::shared_ptr<std_srvs::srv::Empty::Request> request,
    const std::shared_ptr<std_srvs::srv::Empty::Response> response)
  {
    (void)request_header;
    (void)request;
    (void)response;
    RCLCPP_INFO(this->get_logger(), "got request");
    auto req = std::make_shared<std_srvs::srv::Empty::Request>();
    client_->async_send_request(req);
    rclcpp::shutdown();
  }

  rclcpp::Service<std_srvs::srv::Empty>::SharedPtr srv_;
  rclcpp::Client<std_srvs::srv::Empty>::SharedPtr client_;
};

int main(int argc, char * argv[])
{
  rclcpp::init(argc, argv);

  rclcpp::executors::SingleThreadedExecutor exec;
  auto pong_node = std::make_shared<PongNode>(rclcpp::NodeOptions());
  exec.add_node(pong_node);

  printf("spinning\n");
  exec.spin();

  // Will actually be called inside the node's service callback
  rclcpp::shutdown();
  return 0;
}