Handling Stdin and Stdout in a ROS2 Node Launched via a Launch File: Is Switching to a Service Call the Right Approach?

Question

I have a simple ROS 2 node written in C++ that interacts with the user using the cin command. The node expects a basic string input like "yes" or "no" from the user:

string answer;
getline(cin, answer);

When I run the node using:

ros2 run package_name executable_name 

I can easily interact with the node via stdin and stdout.

However, when I run my node from a launch file (which also performs several other tasks), two issues arise:

1. The stdin interaction doesn't work.
2. Any stdout output doesn't appear in the launch file terminal.

After searching online, I discovered that there are challenges with handling stdin and stdout from launch file.

I’m considering switching to expecting a service call, and interacting through the rqt Service Caller GUI.

Does this approach seem like the right direction?

Answer: I chose to use a service because it's easy to work with through the rqt app

Answer 1

Yes, you can use a service for this, but unless there's a need for a return value, you could equally well simply use a topic, or a parameter. It boils down to preference.