Example code for a tutorial at http://blog.tksfz.org/2012/10/12/websockets-echo-using-play-scala-and-actors-part-i/. The interesting code is in app/controllers/Echo.scala.
To run this you need to download the Play Framework at http://playframework.org.
Clone this repo. Then do "play run" in the repo directory. Play will download all the necessary dependencies even the Scala distribution.