Kessin Zachary. Building Web Applications with Erlang: Working with REST and Web Sockets on Yaws

O’Reilly Media, 2012. — 154 p. — ISBN: 978-1449309961.Erlang promises to let you build robust, fault-tolerant servers far more easily than with Java or C#. It almost sounds too good to be true, but Erlang has become a programmer’s secret handshake. As much as many of us hate our phone company, there is a basic truth that must be recognized: when you pick up your phone to make a call, it normally just works. So people have started to realize that telecom folks must be doing something right!
Erlang was built to program telephone switches at Ericsson, and most of the language design choices reflect what was necessary to program a telephone switch. That means, for example, that Erlang software can run for years at a time without interruption because phone switches are expected to do that. Erlang applications can be upgraded in place without taking the system offline or even losing state because the phone company can’t drop a city’s worth of calls every time they have to patch a bug or roll out a new feature.
When a web service goes down, a lot of things break. It may not be as obvious as a suddenly interrupted call, but it may actually create more problems as failures create new failures. Web services can benefit from the language design decisions Erlang’s creators made in a telephone switching environment. Having a server that can run without interruption can allow a development team to provide a better service to their customers.