Vert.x offers event-driven framework for the JVM
Vert.x is built around a "super simple" concurrency model which can allow code to be rewritten as a single-threaded application and removes the need for explicit locking or synchronisation. The system also offers the ability to scale seamlessly over available cores without forking multiple processes by exploiting the JVM's scaling abilities. Other features include a MongoDB-based persistor for data storage.
Tim Fox, lead developer on Vert.x, is a Senior Staff Engineer at VMWare and Vert.x development is sponsored by VMware. The focus of future application development will be on mobile and embedded applications which need large amounts of scaling, with an emphasis on being used in any JVM-hosted language. An embedded version of the platform is also available to add the async framework handling to existing applications.