Non blocking, composable reactive web programming with Iteratees in Play2

Being a part of the wild wild web, your application is encompassed by a lot of streams of live business, social events and messages on top different protocols and technologies including long-polling, comet, and websockets. It is becoming hard for any modern application to resist integrating into these flows of data. To do so, however, you need the appropriate paradigm with a composable model to consume, combine, forward and publish these live streams with minimal and predictable consumption of resources (CPU, memory, ...).
Play2, a web framework targeting Java and Scala, uses functional programming and a model called Iteratee to respond to these needs.