Generating from ros2 .msg file format [13830]

[Nir-Az]

Hi,

I wish to generate code from a ros2 .msg file using fastddsgen.

1. When I try to input the .msg file (that only has 1 line inside "string name") and execute fastddsgen I gen a syntax error.
2. If I create an idl file using OMG syntax for it it works, but using the -typeros2 flag doesn't change anything, the output files stay the same with/without it.
   I expected to see something different, shouldn't I?

Thanks
Nir

[RFRIEDM-Trimble]

In ROS2 galactic release notes, they add a note about this.

Testing this out, here's what I did.

Create the message file

mkdir -p demo/msg
cd demo
cat << EOF > msg/Demo.msg
std_msgs/Header header
geometry_msgs/Twist twist
geometry_msgs/Accel accel
EOF

Run the generator

rosidl generate -o gen -t c -t cpp -t py -I$(ros2 pkg prefix --share std_msgs)/..   -I$(ros2 pkg prefix --share geometry_msgs)/.. demo msg/Demo.msg

View the idl file in the tmp directory

cat gen/cpp/tmp/msg/Demo.idl 
// generated from rosidl_adapter/resource/msg.idl.em
// with input from demo/msg/Demo.msg
// generated code does not contain a copyright notice

#include "geometry_msgs/msg/Accel.idl"
#include "geometry_msgs/msg/Twist.idl"
#include "std_msgs/msg/Header.idl"

module demo {
  module msg {
    struct Demo {
      std_msgs::msg::Header header;

      geometry_msgs::msg::Twist twist;

      geometry_msgs::msg::Accel accel;
    };
  };
};

Note: You can see the includes looking for IDL files at the above paths; I am not yet sure how add /opt/ros/galactic/share to the IDL include path if you wanted to run fastddsgen.

find /opt/ros/galactic/ | grep Twist.idl
/opt/ros/galactic/share/geometry_msgs/msg/Twist.idl

[JLBuenoLopez]

Fast DDS-Gen is a tool independent from ROS 2 and it supports generation of Fast DDS TypeSupports from the OMG defined IDL format. I am afraid that it is not planned to support ROS 2 .msg format nor the -typeros2 option is intended for the described use in this ticket. I think that ROS 2 has a tool to transform from .msg to IDL files.