param_client.cpp

#include <chrono>
#include <iostream>
#include <memory>
#include <string>

#include "rclcpp/rclcpp.hpp"

#include "rcl_interfaces/srv/describe_parameters.hpp"
#include "rcl_interfaces/srv/get_parameter_types.hpp"
#include "rcl_interfaces/srv/get_parameters.hpp"
#include "rcl_interfaces/srv/list_parameters.hpp"
#include "rcl_interfaces/srv/set_parameters.hpp"
#include "rcl_interfaces/srv/set_parameter_types.hpp"
#include "rcl_interfaces/srv/set_parameters_atomically.hpp"


using namespace std::chrono_literals;

rcl_interfaces::srv::GetParameters::Response::SharedPtr send_request(
  rclcpp::Node::SharedPtr node,
  rclcpp::Client<rcl_interfaces::srv::GetParameters>::SharedPtr client,
  rcl_interfaces::srv::GetParameters::Request::SharedPtr request)
{
  auto result = client->async_send_request(request);
  // Wait for the result.
  if (rclcpp::spin_until_future_complete(node, result) ==
    rclcpp::executor::FutureReturnCode::SUCCESS)
  {
    return result.get();
  } else {
    return NULL;
  }
}

int main(int argc, char ** argv)
{
  // Force flush of the stdout buffer.
  setvbuf(stdout, NULL, _IONBF, BUFSIZ);

  rclcpp::init(argc, argv);

  auto node = rclcpp::Node::make_shared("param_client");

  auto client = node->create_client<rcl_interfaces::srv::GetParameters>("get_parameters");

  auto request = std::make_shared<rcl_interfaces::srv::GetParameters::Request>();

  //request->depth = 3;

  while (!client->wait_for_service(1s)) {
    if (!rclcpp::ok()) {
      RCLCPP_ERROR(node->get_logger(), "Interrupted while waiting for the service. Exiting.");
      return 0;
    }
    RCLCPP_INFO(node->get_logger(), "service not available, waiting again...");
  }

  auto result = send_request(node, client, request);

  rclcpp::shutdown();
  return 0;
}