Groovy 2 Cookbook

Using actors to build message-based concurrency

The concept of actors as a strategy for running concurrent tasks has recently gained new popularity (thanks to Scala, Erlang, the Akka Framework, and other programming languages). Originally proposed by Carl Hewitt in 1973, actors offer a programming model that inherently guarantees concurrent code when compared with the traditional approach based on shared memory. Actors are similar to Object-Oriented objects (they follow the rule of encapsulation), but they can only communicate by sending immutable messages asynchronously to each other. The internal state of an actor is not exposed and can only be accessed from the outside by sending a message to the actor and receiving a reply.

Due to the asynchronous ...