Prerequisite Checkpoint: Choose the Interaction Shape

This route assumes you already know ROS 2 topics, services, actions, and parameters from ros2-for-students.

The bridge question is not command syntax. It is whether the interaction pattern fits the system contract.

Given a requirement, choose among:

• topic for ongoing data flow;
• service for bounded request/response;
• action for long-running goal work with feedback/cancel semantics;
• parameter for node configuration.

For each choice, record:

interaction need:
chosen ROS pattern:
why it fits:
what evidence would verify the runtime relationship:

Do not select a mechanism because it is familiar. Select it because the communication semantics match.

If the four ROS patterns are not already familiar, return to the prerequisite course. This bridge keeps only the design decision.