Very quick response as im very busy, hope this helps.
<mx:Application xmlns:mx="
http://www.adobe.com/2006/mxml" width="100%" height="100%" creationComplete="srv.send()">
// to automatically refresh the page on creation complete, or
...
<mx:Button label="Refresh Page" click="srv.send()"/>
//... to do it on a button click
<mx:Script>
<![CDATA[
import mx.collections.ArrayCollection;
[Bindable]
public var myData:ArrayCollection;
]]>
</mx:Script>
<mx:HTTPService id="srv" url="../data/data.xml"/>
//then reference this data source with
<mx:ColumnChart id="chart"
dataProvider="{srv.lastResult.data.result}"
etc.