Professional BlazeDS: Creating Rich Internet Applications with Flex® and Java®

1.1. Introducing Flex through Its Controls and Containers

Flex is an RIA development framework. It provides a set of controls, services, and utilities, which can be readily used together to create rich and engaging applications. Developers programming in Flex use ActionScript 3 (AS3) and MXML to create user interfaces, consume data, provide interactivity, and maintain state.

AS3 is an object-oriented programming language that has a close resemblance to the Java and JavaScript programming languages. MXML is an XML-based declarative language, which makes programming intuitive and easy. All MXML code is translated automatically to AS3 before it's compiled. This intermediate AS3 representation of the MXML code is often deleted unless a developer specifies that that it be saved. Generated AS3 representations of MXML can be saved by explicitly specifying the "-keep" option to the Flex compiler. AS3 compiles to a byte code format called "swf," that runs within the Flash Player virtual machine.

Figure 1-1 shows the essential parts of the Flex framework in a diagram. A Flex application, on compilation, can output a swf file that is ready to run in a Flash Player, or it can output a swc file that can be consumed as a library and made part of a swf file. A swf file can be dropped into a web server and accessed over the web using the standard HTTP protocol. When accessed by a user, the swf is downloaded locally to the user's machine and played in the local browser that hosts the Flash Player. ...