ros2_msgs_common #

Pre-generated Dart classes for the ROS 2 interface packages a robot UI usually needs, so most apps never have to run the generator.

Built on ros2_client, and designed to complement it: the core types it already bundles — Twist, Pose, PoseStamped, LaserScan, RosImage, Header, OccupancyGrid — are not duplicated here.

Install #

dependencies:
  ros2_client: ^0.1.0
  ros2_msgs_common: ^0.1.0

import 'package:ros2_client/ros2_client.dart';
import 'package:ros2_msgs_common/ros2_msgs_common.dart';
import 'package:ros2_msgs_common/nav2_msgs.dart';

void main() {
  registerStandardMessages();
  registerCommonMessages();
  runApp(const MyApp());
}

Import the package you need. ros2_msgs_common.dart exposes only registerCommonMessages() and deliberately re-exports nothing: ROS reuses type names across packages, and one barrel cannot export two SpeedLimit classes.

What is in it #

221 messages, plus their services and actions, in about 400 KB of source.

Note that geometry_msgs and std_msgs here hold only the types ros2_client does not already provide. Twist comes from ros2_client; Wrench comes from here. Both are in scope at once, and neither shadows the other — a generated class that referenced Twist refers to the client's.

Regenerating #

The output is committed, so nothing here needs a ROS install at build time. To retarget a different distro or add a package:

source /opt/ros/humble/setup.bash
./tool/regenerate.sh

Review the diff afterwards — a distro bump can change field types.

Provenance #

Every type here comes from a stock ros-humble-* apt package. Nothing from a local workspace is included, and tool/regenerate.sh pins AMENT_PREFIX_PATH to /opt/ros/$ROS_DISTRO so it cannot be.

That pin matters. The generator searches AMENT_PREFIX_PATH in order and a sourced workspace overlay comes first, so on a developer machine with a robot workspace sourced, asking for a package the overlay also provides would quietly bake that private fork into a package meant for pub.flutter-io.cn. The generator now prints which root each package resolved from, so the provenance is visible in the run rather than assumed.

To audit the committed output yourself:

# Every ROS type name in the package, mapped to the apt package that owns it.
grep -rhoE "'[a-z0-9_]+/(msg|srv|action)/[A-Za-z0-9_]+'" lib/src/msgs/*.dart \
  | tr -d "'" | cut -d/ -f1 | sort -u \
  | xargs -I{} sh -c 'dpkg -S /opt/ros/humble/share/{} 2>/dev/null || echo "{} NOT APT"'

Generated from ROS 2 Humble's .msg, .srv and .action definitions with dart run ros2_client:generate. Those definitions are published by the ROS 2 project under Apache-2.0 (and BSD-3-Clause for some packages); the generated Dart, and this package's own code, are BSD-3-Clause. Message semantics, field names and constants belong to their upstream authors.

Not here #

Types for your own robot's custom interfaces. Generate those:

# From source:
dart run ros2_client:generate -o lib/msgs -s ~/ws/install my_robot_msgs

# Or straight from the running robot, with no ROS install at all:
dart run ros2_client:generate -o lib/msgs -r ws://robot.local:9090 my_robot_msgs

They compose with this package the same way it composes with the client.