This is for the developers who want to start developing a Flex application and want to know what they need for developing a Flex application. For more details about Adobe Flex, check out these blogs What is Adobe Flex and Why Adobe Flex.
All you need to develop an Adobe Flex application are
1. Flex Software Development Kit (SDK) (Required)
2. Knowledge of Action Script 3 and MXML (Required)
3. Flex builder IDE (Optional)
4. LiveCycle Data Services or Blaze Data Services (Optional)
5. Flash player (Required)
How to develop
You develop Adobe Flex applications using MXML and Action Script 3. Once the application is developed, you compile the application using compiler in the SDK into either SWF or SWC. The SWF is the compiled form of the Adobe Flex application and will run on the Flash player. SWC is an archive for flex components and other assets.
Flex SDK contains core component library, development languages, and compiler for Flex applications.
ActionScript 3 (AS3)
ActionScript 3 is a powerful, object-oriented programming language. ActionScript 3.0 is used for rapidly building rich Internet applications. With ActionScript 3.0, developers can achieve excellent productivity and performance with content and applications that target Flash Player. In a Flex application you use AS3 to write programmatic logic for responding to both user-initiated and system-initiated events at runtime.
MXML is a XML based markup language. You use MXML to lay out user interface components in the Adobe Flex application. You can also use MXML to declaratively define non-visual aspects of an application, such as access to data sources on the server and data bindings between user-interface components and data sources on the server.
Flex Builder IDE
This is an Eclipse based IDE used for developing Rich Internet Applications using Adobe Flex. Flex Builder is not free. Using Flex Builder makes the development a lot easier.
BlazeDS is the server-based Java remoting and web messaging technology that enables developers to easily connect to back-end distributed data and push data in real-time to Adobe Flex and Adobe AIR applications for more responsive rich Internet application (RIA) experiences. BlazeDS is available free of cost for download.
LiveCycle DS is similar to BlazeDS but provides a lot more features than BlazeDS.
Flex applications will run on the Flash player. You will need Flash player to run a compiled Flex application.
What do you need to buy?
You need not buy anything for developing a Flex application. If you want to make your development easier then you need to buy Flex Builder IDE.
Check out Flex Developers Guide
Let’s develop Rich Internet Applications