ROS 2 Architecture Overview
Below is a high-level diagram of the ROS 2 architecture.
Data Distribution Service (DDS) Architecture Overview
ROS 2 uses DDS as its middleware. DDS reduces coupling, increases scalability, and improves performance, reliability, security, and flexibility. It is for this reason why it is common to see the DDS communication protocol used in the defense industry.
Below is a high-level diagram of the DDS publish-subscribe communication protocol using an example robotics application.