Configure your Flash application using XML

If you’re anything like me, you don’t particularly enjoy having to launch Flash for a quick little fix, export again and deploy it on a website.

Well using the power of XML you can make your life a lot easier. What I’ll be discussing in this article is the concept of a configuration XML file and how to use it most efficiently for your Flash projects.

Getting started

What exactly is a configuration XML file I hear you saying? It’s not difficult at all; in simple terms what it does is define some properties and corresponding values that overwrite the default values in your Flash application.

Let’s look at an example of such an XML file:

The XML file above shows a typical configuration XML file that allows you to change the companyName and companyLink variables without having to recompile the Flash application.

This XML document is saved as config.xml and placed in the root folder of your Flash application. Of course that’s not enough to get it to work; we need a little bit of code in the Flash application to load in the XML and get hold of the configuration parameters which we’ll look at next.

Getting the configuration parameters

Now we've loaded in the configuration XML file, we need some way to retrieve the parameters. Let's look at the function that does this for us:

getConfigParam = function(param:String) {
  var tmp = configXML["idMap"][param];
  if(tmp == undefined) {
    tmp = this[param];
  } else {
    tmp = tmp.attributes["value"];
  }
  return tmp;
}

The idMap property is new in Flash 8 and allows you to easily access XML nodes that have an id attribute defined.

Using the argument that gets passed to the getConfigParam function we check if the parameter is defined in the XML document, if not use the default value stored in the FLA.

This also explains why we need the same variable names in the FLA as the id attributes in the XML file.

Let's see what the initApplication function does that we called after the configuration XML finished loading:

initApplication = function() {
  var titleText:String = "<a href=\"";
  titleText += getConfigParam("companyLink")+"\">";
  titleText += getConfigParam("companyName")+"</a>";
  companyName_txt.htmlText = titleText;
  loadVideo();
}

In the initApplication function we use the getConfigParam function to retrieve the title and construct a hyperlink to the website defined in the companyLink variable. This hyperlink is then assigned as the htmlText of the companyName textfield.

If the companyLink and companyName variables weren't defined in the configuration XML file what the hyperlink would look like is:

<a href="http://www.visitmehere.com">My Default Company</a>

In this case however both the companyLink and companyName variable are defined in the XML file, so those override the default values and the hyperlink looks like:

<a href="http://www.dmxzone.com">DMXzone</a>

What makes this approach so interesting is that any time you use a variable you might want to change later on without recompiling the application, you call it through the getConfigParam function.  If it is defined in the XML it will use that, if the XML for whatever reason failed to load or the parameter isn't defined it will simply use the default one.

One thing to take into consideration is that you have to make a balance between what is useful to put in the configuration XML file and what is not. If you start putting all your variables inside the XML file this will have the negative side effect of having to load a large XML file before starting your application.

Also be sure never to put any sensitive information in the XML file such as passwords or URLs to Flash Remoting gateways or Flash Communication server connections. While that might be good for testing purposes (you can quickly change between different servers without recompiling) it is not really a secure way for deploying your applications to the web.