Unit Mission: Map the Running System

Your job is to start a small ROS 2 system and explain it without reading Turtlesim source code.

Required system

Run at least:

ros2 run turtlesim turtlesim_node
ros2 run turtlesim turtle_teleop_key

You may also include the second-turtle/remapping exercise.

Required evidence

Use:

ros2 node list
ros2 node info /turtlesim
ros2 node info /teleop_turtle
ros2 topic list

and either rqt_graph or a text graph.

Build the map

Your map must distinguish:

• package names;
• executable names;
• live node names;
• at least one topic;
• publisher direction;
• subscriber direction.

Example structure, not the answer to copy:

PACKAGE
  └─ executable → /node_a
                    │
                    └─ publishes → /topic_x → /node_b subscribes

Controlled change

Apply one runtime name change or remap, then collect the same evidence again.

Mark what changed and what stayed the same.

Defense questions

Be ready to answer:

1. How do you know these nodes were alive?
2. How do you know the connection existed?
3. What is the difference between an executable name and a node name?
4. What did remapping change?
5. What evidence would you collect if a node expected by the diagram was missing?

If you can answer those from the running system, you are ready to study the communication edges themselves.