Reactive systems are found everywhere. The temptation to implement them with legions of waiting threads can be strong; however, the result is nearly always disappointing. The Boost.Asio library provides a framework to handle asynchronous resources with specific classes directed toward networking, serial port I/O, timers and more. In this session we will introduce Asio and some best practices while implementing a simple TCP client and server. Asio has been submitted to the C++ Standards Committee for inclusion and can be found in the Boost library collection or as a stand-alone version. Come and learn a better way to implement reactive systems with the Asynchronous I/O library.