Client and server share an updatable object called context C, initially set to an empty object {}. Upon connection, server defines function C.timer(interval), and client defines function C.deep.tick(reason). Once 'Start' below is clicked, client calls C.timer(2000) and server starts to call client's C.deep.tick('tick') every 2000ms. Client reports ticks to the bottom of this document.
Look at the server source, and the context source.
Start the timer. Stop the timer.
We also can Update everyone's context. This will update all currently connected clients as well as future clients. Check the content of newly set context's `that` property (should equal to 'is available to everyone').