Single-machine "hello world" talker/listener
A minimal ROS system will have a roscore name service, a single publisher node (talker), and a single subscriber node (listener). For purposes of demonstration, we suggest running each of these in their own terminal:
Terminal 1
cd ~/sros source install/setup.bash sroscore --keyserver
Terminal 2
cd ~/sros source install/setup.bash srosrun rospy_tutorials talker
Terminal 3
cd ~/sros source install/setup.bash srosrun rospy_tutorials listener
Commentary
You should now see "Hello, World!" messages being sent from Terminal 2 to Terminal 3 using SSL (more specifically, TLS v1.2). All of the negotiations to set up that connection were also done over SSL, and the sroscore processes was generating self-signed keys as necessary. The default storage location for these keys is ~/.ros/keys, where each ROS node has its own subdirectory for its "key store."
When you're done, type Ctrl+C in each terminal to stop them. Note that this mode of operation currently uses an unsecured XML-RPC server to bootstrap key generation and distribution. To actually run this demo securely, you need to omit the --keyserver argument from sroscore to leave the keyserver disabled by default:
Terminal 1, in secure mode
cd ~/sros source install/setup.bash sroscore