The traditional pull model adopted by the Web, which is used to browse HTML pages now needs to be seconded by two-way communication. This includes a push model where users, for example, receive confirmation of asynchronous and long-running services or just get notifications of various natures.

The recently created Reactive Manifesto, which is available at http://www.reactivemanifesto.org, aims to summarize the criteria that characterize reactive applications in a technology-agnostic way:

Without going into the details of the manifesto that you are encouraged to read, we can directly see that the notion of message-driven architecture, which was...