RIFE offers an alternative approach to web application development and design. It builds upon the Java platform, but offers all required tools and APIs to implement and perform all common Web site related tasks in a fast, intuitive, and consistent manner. RIFE is composed out of a large collection of modular parts, including a Web application engine, integrated Web continuations, a customizable multi-format template engine, support for template content transformation, and more.
Restlet is a REST framework for Java. It supports all REST concepts (Resource, Representation, Connector, Component, etc.) and is suitable for both client and server Web applications. It supports major Web standards like HTTP, SMTP, XML, JSON, WADL, and Atom. Many extensions are also available to integrate with Servlet, Spring, Jetty, Grizzly, Simple, JAXB, JAX-RS, JiBX, Velocity, or FreeMarker. A GWT version is also available.