The code, once again, goes inside the application block. The RemoteObject tag has an ID, which allows us to access it in code, a destination that is a special distinguisher, and the source. The source is the Web location of your CFC. When accessing the CFC remotely, it must be Web accessible (unless you change settings to allow you to access CFCs via a ColdFusion mappings, but such a configuration is beyond the scope of this article). Inside the RemoteObject block there is one method that we respond to: "GetHello". The mx:method tag accepts two arguments: a name and the result. The name is the name of the method on the CFC. The result is the name of a local method that will be called when the Flash Player gets the results from calling that event.

The next step in our code base is to write the GetHello_Handler, which is written in ActionScript. You can put ActionScript in a MXML page using the mx:Script tag:

<mx:Script>
<![CDATA[
    import mx.rpc.events. ResultEvent;
    import mx.utils.ObjectUtil;

private function GetHello_handler( event:ResultEvent):void {
    Result.text = ObjectUtil.toString(event.result);
    }
]]>
</mx:Script>

After the script tag comes the CDATA. This tells the XML parser to ignore the text in the script tag. ActionScript is not a valid XML dialect. (I'm not saying that's bad, though.) Then I import the two objects that are used in the function. Importing objects in this manner is not common in ColdFusion development, but if you've worked with older versions of ActionScript or Java, you've probably seen it. It just says, "I need this object, so make it available to me."

The function should look similar to a CFScript function; I specified the function as private. Then comes the function keyword, followed by the name of the function. Next comes the list of arguments. This function only has a single argument, the ResultEvent. Then comes a colon followed by the return type. This function doesn't return anything. The one line of code takes the result from our function call, translates it to a string, and assigns it to the text of our Result label. It sounds more complicated than it actually is.

Type in the code (or copy and paste from the Web version), compile it, and execute it. You should see something similar to Figure 1. Click the button. Unfortunately nothing happened as the button was not told what to do yet. A click event needs to be added to the button. The new button code will look like this:

<mx:Button x="154" y="56" label="Get Hello" click="helloWorld.GetHello()"/>

The click event refers to the helloWorld remote object and says, "Execute the GetHello" method on that object. You should recognize this syntax for calling the method from your use of CFCs inside ColdFusion. When the button is clicked, the Flash player goes to the remote object and calls the method. When the method result is returned, the Flash player looks for the "mx:method" tag and executes the result function. Recompile the code and try it out. Click the button and you should see the Hello World text display next to the button (see Figure 2).

Conclusion
Adobe has done a fantastic job of making ColdFusion the best back-end tool for developing Flex applications. Included with Flex Builder are some Eclipse extensions that work well with ColdFusion, including RDS support and some code generators. I'm just scratching the surface of what can be done with Flex and how you can combine it with ColdFusion. I'd love to see what you are going to do with this technology, so be sure to let me know! See you in a month.