Reasonable Server Faces is an open source web programming framework written in Java

Java (programming language)

Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...

, developed at the Centre for Applied Research in Educational Technologies (CARET) at the University of Cambridge

University of Cambridge

The University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...

. RSF is built on the Spring framework, and allows views to be templated in pure XHTML, as well as other XML dialects. RSF takes responsibility for the entire request processing cycle through HTTP request decoding, maintaining a bean model, invoking actions, directing errors, intepreting results and rendering views. A principal aim of RSF is to facilitate designs where zero server state is held in between requests.

RSF is notable for its extremely lightweight component model, a request-scope Inversion of Control

Inversion of Control

In software engineering, Inversion of Control is an abstract principle describing an aspect of some software architecture designs in which the flow of control of a system is inverted in comparison to procedural programming....

 layer (RSAC) modelled on the Spring framework, and a pure HTML templating engine, IKAT.