Flex uses two programming languages: MXML and ActionScript.
MXML is unique to Flex and designed specifically to describe properties in Flex layouts, though it’s not limited to describing visual objects. MXML is an extension of XML, where each tag represents a different Flex component. You can nest components inside each other to provide a variety of different layout and interface options. Other nonvisual components, such as web services interfaces, transitions, and style sheet specifications can also be written in MXML.
You can write ActionScript 3.0 methods to process data, react to events, perform transitions, or even draw shapes and components on the screen. It’s customarily implemented to enhance the functionality of MXML components.
ActionScript and MXML work very nicely together. While all Flex applications must begin with at least a single MXML file, ActionScript can be nested within MXML components or imported from separate files. In the intended implementation, MXML provides the structure and organization in an application, while ActionScript provides access ...