A lot of people steer clear of the Flex framework because they think it’s complicated. But generally speaking, a framework is just a set of reusable classes that can work together to provide a base for an application.
Take a house as an analogy: every house on the planet has a framework. Each house has a foundation and walls, and those walls can’t stand without the foundation. Once the foundation has been laid and the walls are up, a roof can be applied and the interior designed and implemented, while work continues on the initial foundation.
If we apply this analogy to the Flex framework, we have a stack of logic — the controller logic — that has been made available for communicating with a database, handling security, writing to the file system, and so on. There are also the user interface elements — buttons, canvases, dropdown lists, and so on. All of these also form the foundation of your Flex application — the concrete slab, the timber beams and the bricks with which to build your house.
Flex is easy for web developers to learn because, at its core, it has a lot in common with (X)HTML, CSS, and JavaScript. Suppose you wanted to create a simple web page with a form button. In XHTML you’d type the following:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>
<html xmlns=”http://www.w3.org/1999/xhtml”>
<head>
<meta http-equiv=”Content-Type” content=”text/html; charset=utf-8″ />
<title>Button Example</title>
</head>
<body>
<form method=”post” id=”example” action=”http://www.example.com/”>
<input type=”button” name=”newButton” id=”newButton” value=”This is a button” onclick=”checkForm()” />
</form>
</body>
</html>
To display something similar in Flex we use a form of markup called MXML. Here’s the MXML markup for our previous example:
<?xml version=”1.0″ encoding=”utf-8″?>
<mx:Application xmlns:mx=”http://www.adobe.com/2006/mxml”
layout=”absolute”>
<mx:Button x=”10″ y=”10″ label=”This is a button”
id=”newButton”
click=”checkForm()”/>
</mx:Application>
(+2)
