ROS2 Humble Tutorial Workspace

A complete teaching workspace covering the fundamentals of ROS2 Humble with both C++ (rclcpp) and Python (rclpy) examples.

Each concept lives in its own package. Build them all at once with colcon build, or build a single one with colcon build --packages-select <name>.

Author: agus-darmawan <darmawandeveloper@gmail.com> License: BSD-3-Clause (see LICENSE)

Curriculum overview

Follow the suggested order. Each package is prefixed pkgNN_ so the lessons appear in order in the filesystem. The prefix is part of the actual ROS2 package name — it's how you import, build, and run them.

#	Package	Concept	Language
1	pkg01_topic_cpp	Publisher / Subscriber	C++
2	pkg02_topic_py	Publisher / Subscriber	Python
3	pkg03_tutorial_interfaces	Custom msg / srv / action definitions	IDL
4	pkg04_service_cpp	Services (client / server)	C++
5	pkg05_service_py	Services (client / server)	Python
6	pkg06_action_cpp	Actions (long-running tasks)	C++
7	pkg07_action_py	Actions (long-running tasks)	Python
8	pkg08_parameters_cpp	Node parameters	C++
9	pkg09_parameters_py	Node parameters	Python
10	pkg10_tf2_cpp	TF2 — coordinate frames	C++
11	pkg11_tf2_py	TF2 — coordinate frames	Python
12	pkg12_launch_examples	Launch files (minimal, args, namespaces)	Python launch

Build pkg03_tutorial_interfaces before the service/action packages — they depend on it. colcon build figures out the order automatically.

Prerequisites

# Ubuntu 22.04 + ROS2 Humble
source /opt/ros/humble/setup.bash

sudo apt install \
  ros-humble-rclcpp \
  ros-humble-rclpy \
  ros-humble-std-msgs \
  ros-humble-geometry-msgs \
  ros-humble-sensor-msgs \
  ros-humble-tf2 \
  ros-humble-tf2-ros \
  ros-humble-tf2-geometry-msgs \
  ros-humble-turtlesim \
  python3-colcon-common-extensions

Build the whole workspace

cd ~/ros2_tutorial_ws
colcon build --symlink-install
source install/setup.bash

--symlink-install lets you edit Python files and re-run without rebuilding.

How to use this material

1. Start with pkg01_topic_cpp, then pkg02_topic_py. Read the README first.
2. Build pkg03_tutorial_interfaces before moving to services/actions.
3. Run each example in 2–3 terminals — ROS2 nodes are independent processes.
4. Use ros2 topic / service / action / node / param CLI tools constantly. They are your debugger.

ROS2 big picture (cheat sheet)

┌─────────────────────────────────────────────────────────────┐
│                       ROS2 Concepts                          │
├─────────────────────────────────────────────────────────────┤
│ Node       → a process that does one job                     │
│ Topic      → many-to-many async stream (sensor data)         │
│ Service    → one-to-one sync request/response (queries)      │
│ Action     → long-running task with feedback (navigation)    │
│ Parameter  → tunable values on a node                        │
│ TF2        → tree of coordinate frames over time             │
│ Launch     → start many nodes with config in one shot        │
└─────────────────────────────────────────────────────────────┘

Rule of thumb for picking a primitive:

• Continuous data flow → Topic
• Quick "give me an answer now" → Service
• "Do this for a while and tell me how it's going" → Action
• Robot poses / sensor mounting → TF2
• Numbers you want to tune without recompiling → Parameter

CLI quick reference

ros2 node list / info <node>
ros2 topic list / info / echo / pub / hz
ros2 service list / type / call
ros2 action list / info / send_goal
ros2 param list / get / set
ros2 interface show <type>
ros2 launch <pkg> <file>
rqt_graph     # visualize the node/topic graph
rqt           # general GUI dashboard

Suggested next topics (not in this workspace)

When the students are comfortable with the above, the natural next steps are:

• Lifecycle (managed) nodes — nodes with a state machine for clean startup/shutdown.
• Executors & callback groups — concurrency, callback isolation, real-time priorities.
• QoS (Quality of Service) profiles — reliability, durability, history depth for topics.
• Composition — running multiple nodes in one process for zero-copy speedup.
• rosbag2 — recording and replaying topic data.
• URDF + robot_state_publisher — robot description and full TF tree publishing.