Page 1 of 2   next page »

We've all seen Google finance, and the great job that it does at mixing HTML content with Flash content, as seen on company stock quotes. Google has done a great job at using Flash where it makes the most sense, in the graphs for company quotes, with HTML where it makes sense (linking to news items). Today, I'll show you how to build your own Google-finance type site, using a combination of Ajax, JSON, PHP and Flex / Flash. And, best of all, we'll do it all for free.

In this example, we'll grab data from a Feedburner feed, and then show the hits to that feed in a graph, over time. We'll bring in the RSS information from our blog feed, and when we click on the items in the graph, they'll highlight the RSS feed items for that day.

To complete this tutorial, you'll need the following software / accounts:
1.  Note: You can perform this same tutorial without Flex Charting. You would need to create your own Flex component, and you could do that with the SDK. So, technically this tutorial could be accomplished for $0. In my case, to reduce development time, I'm using the Flex Charting components, which cost $249.

The first part to this tutorial is to install all the above software. I won't go through that here, if you have problems please comment in my blog.

Believe it or not, there actually are pieces of Adobe software that I don't use, feel free to use Photoshop to design the appearance of the webpage, Lightroom to hold photos of pepople you will put on the HTML page, Premiere to do video editing, ColdFusion can replace the PHP part fairly easily etc... I leave it up to you to extend this tutorial to make use of every piece of Adobe software.

Once we've got everything installed, we'll start by hooking up our PHP backend to Spry. The reason that we need the PHP backend is because Ajax applications cannot load data from outside sources: we need to load data from the same source as the Ajax application. So, we've created a small PHP file that will go to Feedburner, get the stats and then print the output. That PHP file is very small and very simple:

<?php
$fpURL = 'http://api.feedburner.com/awareness/1.0/GetFeedData?uri=adobe/
mpotter&dates=2006-07-01,2006-07-17';
$handle = fopen($fpURL, "r");
while (!feof($handle)) {
$strOutData .= fread($handle, 8192);
}
fclose($handle);
header('Content-type: text/xml');
echo $strOutData;
?>

Any server side language could do something similar.

And here's the JavaScript code for Spry to call and load that PHP file:

var dsFeedburner = new Spry.Data.XMLDataSet("getdata.php", "/rsp/feed/entry");

When the HTML page loads, it will call getdata.php, and populate the Spry dsFeedburner data source with data from that file. Here's a sample of the XML content that gets output from that PHP file.

<?xml version="1.0" encoding="UTF-8"?>
<rsp stat="ok">
<!--This information is part of the FeedBurner Awareness API.
If you want to hide this information, you may do so via your FeedBurner Account.-->
<feed id="412263" uri="adobe/mpotter">
<entry date="2006-07-01" circulation="0" hits="0"/>
<entry date="2006-07-02" circulation="0" hits="0"/> ...

The text "/rsp/feed/entry" is simply an xpath expression to get to each <entry... item in the XML file.

So, now we've got the data. To populate a table with data, we do the following:

<table border="1" spry:region="dsFeedburner">
<tr>
<th onClick="dsFeedburner.sort('@date');">Date</th>
<th onClick="dsFeedburner.sort('@hits');">Hits</th>
</tr>
<tr onclick="alert({@date});" spry:repeat="dsFeedburner" spry:select="SelectedFeedburnerItem"
spry:hover="HoverFeedburnerItem"> <td>{@date}</td>
<td>{@hits}</td>
</tr>
</table>

We repeat each table row (<tr>) with the spry:repeat="dsFeedburner" attribute. We set the selected item's CSS class to "SelectedFeedburnerItem", and the hover state to "HoverFeedburnerItem". You can edit the style for those items with simple CSS, in the HTML file (or an external CSS file, whichever you prefer.)

OK, so if we run that, then we should see a repeatable table showing dates and hits to our items. Pretty good, now let's hook that up to a graph component that we made in Flex.

Its important to note here that Flex can be used to create a number of components. Its possible, with a little work, that you could create a component that exactly matches the graphing component that Google uses, with a date slider / selector at the top, above the graph. I won't do that here, for the sake of simplicity, but it is possible. Or, you could create an Ajax media browser that plays videos in Flash. The possibilities are limited only by your imagination.

So, let's go ahead and create our Flex graph... Here's the MXML code:

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" width="400" height="400"
backgroundGradientColors="[#ffffff, #ffffff]">
<fab:FABridge xmlns:fab="bridge.*" />
<mx:Script>
<![CDATA[
import mx.charts.events.ChartItemEvent;
import mx.collections.ArrayCollection;
import com.adobe.serialization.json.JSON;
public function bindJSONToChart( JSONString:String ):void {
var arr:Array = (JSON.decode(JSONString) as Array);
linechart.dataProvider = new ArrayCollection(arr);
}
public function chartClicked(clickEvent:ChartItemEvent):void
{
if( ExternalInterface.available )
ExternalInterface.call("chartClicked", clickEvent.hitData.item);
}
]]>
</mx:Script>
<mx:LineChart id="linechart"
paddingLeft="5" paddingRight="5"
showDataTips="true" left="10" right="10" top="10" bottom="10" itemClick="callEI(event)">
<mx:horizontalAxis>
<mx:CategoryAxis categoryField="@date" displayName="Date"/>
</mx:horizontalAxis>
<mx:series>
<mx:LineSeries yField="@hits" displayName="Hits"/>
</mx:series>
</mx:LineChart>
</mx:Application>

Everything should be fairly self-explanatory. The only lines that may be unfamiliar are:

<fab:FABridge xmlns:fab="bridge.*" />
which is needed for the Flex / Ajax bridge to function properly and:
public function callEI(func:String, clickEvent:ChartItemEvent):void
{
if( ExternalInterface.available )
ExternalInterface.call("chartClicked", clickEvent.hitData.item);
}
which is needed to call back to the page that contains the Flash file, in our case the Ajaxed HTML page.
OK, so we've got our Flex application built, we've got our Ajax file, now we need to pass data from the Ajax page to
the Flex application. Here's how you do that in JavaScript:
var obs = new Object;
obs.onPostLoad = function(notifier, data)
{
Spry.Debug.trace("obs.onPostLoad called!");
};
var notifierData;
obs.onDataChanged = function(notifier, data)
{
notifierData = notifier.data;
try {
with( FABridge.example.root()) {
bindJSONToChart( jsmin( toJsonString( notifier.data ) ) );
}
}
catch( e )
{
var initCallback = function( )
{
with( FABridge.example.root() ) {
bindJSONToChart( jsmin( toJsonString( notifierData ) ) );
}
}
FABridge.addInitializationCallback("example",initCallback);
//alert( "Error in onDataChanged"+e );
}
Spry.Debug.trace(toJsonString( notifier.data ));
};
dsFeedburner.addObserver(obs);

There's lots going on here. First, we create an observer on the data's "onDataChanged" method, so every time the data is changed, we send new data to the Flex application. Although we only use this once, when the page is loaded, you could use this if you had say a drop down list of a number of your feeds, and wanted the data source to change when the drop down changed. When you changed your Spry data source, the Flex graph would refresh because of this observer.

Page 1 of 2   next page »