Tornado vs. Zend Framework vs. Revel

By using non-blocking network I/O, Tornado can scale to tens of thousands of open connections, making it ideal for long polling, WebSockets, and other applications that require a long-lived connection to each user.

Zend Framework 2 is an open source framework for developing web applications and services using PHP 5.3+. Zend Framework 2 uses 100% object-oriented code and utilises most of the new features of PHP 5.3, namely namespaces, late static binding, lambda functions and closures.

Revel makes it easy to build web applications using the Model-View-Controller (MVC) pattern by relying on conventions that require a certain structure in your application. In return, it is very light on configuration and enables an extremely fast development cycle.