[ROS2] services C++

edit

Hi,

I'm trying to use services to work with a ROS2 canopen node. In ROS1 I was able to use this code:

ros::ServiceClient init = n.serviceClient< std_srvs::Trigger>("/driver/init");

std_srvs::Trigger trig;

init.call(trig)

If I follow the migration guide, I have following code:

rclcpp::Client< std_srvs::srv::Trigger>::SharedPtr client = node->create_client< std_srvs::srv::Trigger>("/driver/init");

std_srvs::srv::Trigger trig;

How do I call the service ?

init.call(trig)

This doesn't work

Edit: (tutorial services)

auto result = client->async_send_request(request);
  // Wait for the result.
  if (rclcpp::spin_until_future_complete(node, result) ==
    rclcpp::executor::FutureReturnCode::SUCCESS)
  {
    RCLCPP_INFO(rclcpp::get_logger("rclcpp"), "Sum: %ld", result.get()->sum);
  } else {
    RCLCPP_ERROR(rclcpp::get_logger("rclcpp"), "Failed to call service add_two_ints");
  }

This calls the service I think, but I need to send a request with it. How Can I call a service without a request? The Service file can only respond with some variables.

Thanks