First start the WEBrick server. Open a command line window (a terminal window or DOS command window, depending upon your operating system).
If you want to see the server's output (page requests and error messages), start the server from the command line by running the script httpd.rb.
Open two Web browser windows. One will be the syndicator, or publisher, and the other with be the subscriber.
If change code, may need to restart Web server and/or delete /tmp/ice-* files (Ruby CGI session data and Ruby pstore data).