I'm going to postpone the second part of my RSS aggregator article to tie this column into this Flex-themed issue. Have no fears, though, it will be back in full force in the next issue. Flex, as I'm sure most people know, is a way for programmers (you, me, and us) to create Flash movies.

 The focus of Flex is not on animation and drawing little fancy pictures; it's on creating advanced interfaces, which are used to create Rich Internet Applications (RIA). It is a "Flash for programmers"-oriented product. Macromedia had long been pushing the concept and benefits of Rich Internet Applications, so it's great to see Adobe taking up the charge and finally making them accessible to all.

Flex 2 was released at Adobe's CFUNITED keynote (a few days ago to me), so this issue seems appropriately timed. I thought I'd take the space in this beginner's column for an overview of Flex 2 and talk about why you want to care.

Putting the Pieces Together
Everyone who has seen Flex from the beginning viewed it as an amazing and revolutionary product. If you think of ColdFusion as a way to build HTML pages on the fly, Flex was a way to build Flash movies on the fly. Unfortunately, most people found the price tag to be a serious setback to Flex usage. Adobe has addressed those concerns head on with the release of Flex 2.

These are the components that make up the Flex 2 suite of products:

• ActionScript 3: The language of Flash has always been ActionScript. With the release of the Flash 9 Player comes a new version of ActionScript. ActionScript has always been used to provide advanced functionality in a Flash movie.
  
• MXML: MXML stands for Maximum Experience Markup Language and is a form of XML. You can use MXML to create Flash movies with Flex. Most things in ActionScript have a parallel in MXML, and vice versa.
  
• Flash 9 Player: Flex applications will run only on Flash Player 9. Flash Player 9 adds support for ActionScript 3, and offers many performance enhancements over Flash 8.
  
• Flex SDK: The Flex SDK is everything you need to build Flex applications. It contains a command-line compiler along with all the built-in Flex components (which includes a bunch of user interface elements). You can write MXML code in any editor of your choice, use the SDK to compile it to a swf file, and then deploy it to a Web server of your choosing. There have been rumors that Adobe hopes the release of the SDK will allow for the creation of third-party tools for generating Flex applications. I haven't heard of any tools being built yet, but this definitely bodes well for the long-term release of the community. Did I mention that the Flex SDK is free?
  
• Flex Builder 2: Flex Builder 2 is an Eclipse-based editor for building Flex applications. Although you can use the Flex SDK to build them for free, Flex Builder offers many advantages, including tag insight and a step-through debugger. Flex Builder is available as a standalone product or as an Eclipse plug-in. I like to use the plug-in version so that my Flex applications can easily reside next to CFEclipse applications.
  
• Flex Charting Components: The Flex charting components are available as a standalone package or as an add-on to Flex Builder. They make it easy for you to generate charts in Flex, as well as allow for drill down and roll over functionality.
  
• Flex Data Services: Flex data services allow you to push data to the browser. It integrates with ColdFusion very nicely through the use of an event gateway. This is a feature that was unavailable in Flex 1.5, and can be very powerful in some applications.

Accessing a CFC from Flex
Flex can call CFCs directly using Flash Remoting; an update to ColdFusion's Flash Remoting components is located in the 7.02 updater. This update helps ColdFusion talk to something you built in Flex. To demonstrate, I'll start with a simple helloworld.cfc:

<cfcomponent>
<cffunction name="GetHello" output="false" access="remote" returntype="string">
    <cfreturn "Hello World">
    </cffunction>
</cfcomponent>

If you are not familiar with CFCs, there are a plethora of resources for learning about them. You might start with one of my previous columns on them at http://coldfusion.sys-con.com/read/47203.htm. This component has no instance variables and only contains a single "GetHello" method. The method returns the string "Hello World." This is simple stuff, and you all know it, right? Great, let's look at some Flex code!

First, you'll need to define a Flex application, like this:

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
</mx:Application>

All the MXML code that you write will go in the mx:Application block. In CFML, all tags start with CF. In MXML, all tags start with "mx:". Code blocks work the same way in either language. The mx:Application works, conceptually, the same way that a cfloop does. Now we can add a label and a button to our code:

<mx:Label id="Result" x="59" y="58"/>
<mx:Button x="154" y="56" label=" Get Hello"/>

Remember that this code goes in the mx:Application block. I used Flex Builder 2 to easily place the label and button, but if you are using the SDK without Flex Builder, you can specify the location of the elements using the x and y coordinates as shown in the code. This code will show you an empty label with a button next to it. The label, at present, doesn't contain any text. The button displays the text "GetHello" but doesn't actually do anything yet. The label is given an ID "result". This is so we can reference it later to assign it a value. I did not give the button an ID because we won't need to access it programmatically.

Next you need to tell Flex how to find your CFC. To do that, I used the RemoteObject tag and placed this code in my MXML file:

<mx:RemoteObject id="helloWorld" destination="ColdFusion" source="htdocs.experiments.flex.helloworld">
    <mx:method name="GetHello" result="GetHello_handler(event)" />
</mx:RemoteObject>