Why does Ubuntu (Source) installation's rosdep skip some keys
While following the Ubuntu (Source) installation, in the Install dependencies using rosdep step, some rosdep keys are skipped as following:
rosdep install --from-paths src --ignore-src -y --skip-keys "fastcdr rti-connext-dds-6.0.1 urdfdom_headers"
What is the reason for skipping these keys? I have gone back through the commit history of the tutorials back to ROS2 crystal, but these keys have existed before that time. I am wondering if the instructions are outdated.
The only logical explanation I can think of, for rti-connext-dds-6.0.1, is that it's not used as the default dds, and the size of the package is significant (154mb).
IIRC, Connext requires a license, which many people may not have, nor is it a default RMW implementation.
fastcdris likely already included as a dependency of FastDDS (but this is speculation).urdfdom_headersI wouldn't know.