Reactive use case - a stock price page

While the Reactive Manifesto helps us understand the characteristics of a Reactive System, it does not really help with understanding how Reactive Systems are built. To understand this, we will consider the traditional approach to building a simple use case and compares it with the reactive approach.

The use case we want to build is a stock price page that displays the price of a specific stock. As long as the page remains open, we want to update the latest price of the stock on the page.

The traditional approach

The traditional approach uses polling to check whether the stock price has changed. The following sequence diagram shows the traditional approach of building such a use case...