Unit 04 · lesson
Bridge Checkpoint: Configuration Is Evidence, Not Integration
A runtime parameter snapshot can tell you what a ROS 2 node reports as configuration. It does not automatically prove a Java-side rule consumes that value.
Suppose the ROS evidence says:
/motor_guard:
caution_distance_m: 0.5And the Java code contains:
private static final double CAUTION_METERS = 0.5;The numbers match. The sources do not.
Separate the claims
Create a small table with these columns:
| claim | evidence source | proved? |
|---|---|---|
| Java threshold equals 0.5 | source/runtime Java evidence | yes |
| ROS parameter equals 0.5 | ROS parameter evidence | yes |
| Java reads ROS parameter | integration path | not yet |
Then list what would strengthen the third claim, such as an observed bridge process, message/config adapter, shared file, API, or another documented mechanism.
Failure thought experiment
Change one side to 0.6. What would you expect to observe if the two systems are truly integrated? What would you observe if they are merely configured independently?
That distinction is the lesson.
If ROS parameter mechanics are unfamiliar, review ros2-for-students. This route assumes the command family is already known and focuses on provenance.