Vert.x is a non-blocking, event-driven Java framework.
Vert.x supports Java, JavaScript, Groovy, and Python. Vert.x is a polyglot framework for developing Java web applications and Java servcies.
Reactive Programming is a oriented around data flows and the propagation of change. Reactive programming is very popular for interactive user interfaces. JavaScript event based programming has become very mainstream due to JavaScript dominance as a web development platform on the client.
Node.js has made this programming model a force to deal with for server-side development. Node.js provides a paradigm that JavaScripts developers are familar with and allows them to quickly develop backend service development.
Like Node.js, Vert.x uses an event-driven, non-blocking I/O model. Like Node.js, Vert.x is lightweight and efficient. Vert.x is the perfect for environment for developing services that are data-intensive, real-time applications, across distributed devices.