What You Need to Start Developing with Apache Flex

To start developing with Apache Flex, you need three things: the Flex SDK, an ActionScript 3 (AS3) coding environment, and an IDE that supports MXML and AS3. Apache Flex uses MXML for layout and AS3—an ECMAScript-based language similar to JavaScript—for coding, and the project points developers to Eclipse-based IDEs such as Adobe Flash Builder and FDT. Before committing, note one important constraint from the official site: Flash Player in the browser is no longer supported by Adobe and the major browser vendors after the end of 2020, so browser-targeted work should be planned around Apache Royale instead, while mobile and desktop output through the Adobe AIR runtime provided by Harman remains supported.

The Core Components

1. The Flex SDK

The SDK is the foundation. The Apache Flex download page lists several options depending on your role:

If you are building applications rather than modifying the framework itself, the Installer is the entry point the project designates for you. Source code and binaries are aimed at people working on the SDK.

2. A Coding Setup: MXML and AS3

Flex separates layout from logic: MXML describes the interface, and AS3 handles behavior. You do not need a separate compiler toolchain beyond the SDK, but you do need an editor or IDE that understands both file types.

3. An IDE

The site names Eclipse-based IDEs—Adobe Flash Builder and FDT—as the tooling to use. The stated advantage is that you can "utilize the tools you are already familiar with," so if you already work in an Eclipse environment, the transition is short.

Learning Resources to Use First

The documentation section of the site organizes material you can work through in this order:

• Getting Started — the natural first stop for setup and a first project.
• Using Flex — usage guidance beyond the basics.
• Videos — visual walkthroughs.
• Flex ASDocs — API reference for the framework classes.
• Developer FAQ — answers to common development questions.
• FlexUnit Tutorials and FlexUnit ASDocs — for unit testing your code.
• Tour de Flex — a showcase of components and techniques, also available as source code.

For community help, the project lists Mailing Lists, a Third-Party Wiki, a Blog, and a Bug Tracker.

Decide Your Target Before You Install

The platform you intend to ship to changes what "getting started" means:

• Browser output — Flash Player browser support has ended. The project explicitly directs browser-targeted work to Apache Royale, its sister project, which lets you keep using ActionScript while outputting native JavaScript and HTML.
• Desktop applications — built on the Adobe AIR runtime provided by Harman, which the site states is still supported.
• Mobile applications — also via Adobe AIR, targeting iOS devices (iPod, iPhone, iPad), Android smartphones and tablets, and BlackBerry Playbook.

So the practical sequence is: confirm your deployment target is AIR-based (desktop or mobile) or plan a Royale migration for browser work; then download the Flex SDK Installer; then set up an Eclipse-based IDE; then work through Getting Started and the ASDocs.

Licensing and Support Context

Apache Flex is completely open source, released under the Apache License, version 2.0, which the project notes is compatible with business needs. It is backed by the Apache Community for updates, support, and help—relevant if you are evaluating whether the framework fits a long-lived project. The site also maintains a Flex Showcase of desktop and mobile applications built with Flex, and you can submit your own application for inclusion.