Flex is a free, open source framework for building highly interactive, expressive web applications that deploy consistently on all major browsers, desktops, and operating systems. MXML, a declarative XML-based language, is used to describe UI layout and behaviors, and ActionScript 3, an object-oriented programming language, similar to Java, is used to create client logic. Flex also includes a rich component library with a lot of predefined UI controls, for example: datagrids, charts, video playback components.
Desktop applications development is based on AIR framework that leverages the existing knowledge in Flex, and adds additional features as: File I/O, Drag&Drop and Clipboard, System Tray, Background applications, Application Update API, and others functionality.
Cairngorm is the lightweight micro-architecture for Rich Internet Applications built in Flex or AIR. A collaboration of recognized design patterns, Cairngorm exemplifies and encourages best-practices for RIA development advocated by Adobe Consulting, encourages best-practice leverage of the underlying Flex framework, while making it easier for medium to large teams of software engineers deliver medium to large scale, mission-critical Rich Internet Applications.
Developers in Pentalog have been using the Cairngorm framework for developing application as for its clients' projects (JuWiMM - Flex and AIR applications), so for internal use (Sites Pentalog - Flex Applications).
WebORB for .NET is a robust, non-intrusive, multi-protocol development and runtime environment that is designed to effortlessly connect Flex, Flash, AJAX and Silverlight clients with .NET objects, XML Web Services, native operating system resources and rich media streams (audio and video). – Community / Entreprise
FluorineFx provides an implementation of Flex/Flash Remoting, Flex Data Services and real-time messaging functionality for the .NET framework. – Open Source, Free, MONO