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. - github

• Event-based Programming
• Thin

• EventMachine-LE

• Embedding Sinatra
• defered event & callback
• em-synchrony
  • Untangling Evented Code with Ruby Fibers
• em-faraday.rb