Akka is an event-driven middleware framework, for building high performance and reliable distributed applications in Java and Scala. Akka decouples business logic from low-level mechanisms such as threads, locks and non-blocking IO. Your Scala or Java program logic lives in lightweight actor objects which send and receive messages. With Akka, you can easily configure how actors will be created, destroyed, scheduled, and restarted upon failure.
Akka is Open Source and available under the Apache 2 License.