Getting Started with Flex
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In this discussion, I will focus on the basics of Flex, a web development framework based on Flash. The first section will be about the whys and wherefores of Flex. The second section will cover the steps involving the development of a Flex-based application. In the third and fourth sections, a real world application using Flex will be developed.
In today's world of interactive and responsive web applications, developers have to choose between Ajax (based on JavaScript and CSS) and Flash. And since Flash is considered a multi-media tool rather than a web UI tool, the majority of developers favor Ajax. However, Ajax has its own set of problems, the most prominent among them being browser compatibility.
The demand for a framework that is flexible as well as interactive and responsive brought forth many frameworks. Most of them were JavaScript-based. However, one of the frameworks is based on Flash. And even though it is based on Flash, its usage does not require knowledge of Flash. It makes use of tags and Action Script. The name of the framework is Flex.
Flex – the whys and wherefores
By definition, the Flex framework is “A collection of technologies released by Adobe Systems for the development and deployment of cross platform, rich Internet applications based on the Adobe Flash platform.” The Flex framework is also known as Flex SDK. The keywords in the definition are "cross platform," "rich Internet applications," and "collection of technologies." Let us look at these in detail.
Cross platform: Flex is based on Flash. Therefore, Flex applications will work on all those platforms for which Flash players are available. At present, Flash players are available for Mac, Linux and Windows. Hence, Flex applications will work on all of them.
Rich Internet applications: By definition, “Rich Internet applications (RIA) are web applications that have the features and functionality of traditional desktop applications.” In other words, RIA provides a paradigm that breaks away from the request-response-page refresh cycle. In RIA, only the request-response cycle exists. All the UI-based processing is shifted onto the client side. This paradigm is also known as the no-refresh paradigm. Since Flex makes use of Flash extensively, developing RIA using Flex scales down the problems associated with RIA.
Collection of technologies: The Flex framework, or SDK, is made up of different technologies. The UI and layout are defined using MXML, which is based on XML. Interaction implementation (or event handling) is done using ActionScript. ActionScript is the language used in Flash and it is based on ECMAScript, or JavaScript.
The definition provides the attributes of Flex. However, it does not tell us what its components and services are. Therefore, let's have a look at the most common components and services of Flex. The components as well as services provided by Flex can be divided into the following categories:
- UI components
- Charting components
- Web and Utility services
The web and utility services provide web service and data access functionalities. Here are the details:
UI Components: This category contains components that can be used to implement the user interface of web applications. This category can be further divided into containers and controls. The former provide layouts and can contain the latter. Controls include textboxes, combo boxes, etc. All of the controls can be controlled using Action Script.
Charting Components: The charting components of Flex extend the Flex framework to provide charting functionalities, including line, bar, and pie charts. One can add drill down, roll over, and other visual effects so that data can be represented visually and dynamically.
Web and Utility Services: Using Flex, one can access Web services and display the data retrieved from the Web service. Apart from this, Flex also provides APIs to implement drag and drop, animation, effects, form validation, and application state management. These utilities are built into the core of Flex. Hence, to use them, one need not learn any third party APIs.
That brings us to the end of this section. In the next section we will discuss the steps necessary to develop an application in Flex.
Next: Developing a Flex Application >>
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