EventMachine
EventMachine, fast, simple event-processing library for Ruby programs
EventMachine is an event-driven I/O and lightweight concurrency library for Ruby. It provides event-driven I/O using the Reactor pattern, much like JBoss Netty, Apache MINA, Python's Twisted, Node.js, libevent and libev. Extremely high scalability, performance and stability for the most demanding production environments. An API that eliminates the complexities of high-performance threaded network programming, allowing engineers to concentrate on their application logic. This unique combination makes EventMachine a premier choice for designers of critical networked applications, including Web servers and proxies, email and IM production systems, authentication/authorization processors, and many more. EventMachine has been around since the early 2000s and is a mature and battle-tested library.