1. CSC 2720 Building Web Applications FLEX –Working with Remote Data

2. Connecting with HTTP  Use HTTPService class to load any remote data via HTTP protocol  Steps:  Create an instance of HTTPService that maps to a URL.  Invoke the send() method to retrieve the remote file asynchronously.  Retrieve the loaded data via the lastResult property.

3. Loading an XML File students.xml

4.  service.lastResult.students.student is an array of objects with each object containing three properties – name, id, age.  The lastResult property holds the most recently retrieved data. <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" creationComplete="service.send()"> <mx:DataGrid dataProvider="{service.lastResult.students.student}" >

5. HTTPService's resultFormat Property  We can specify in what format the returned value should be using the property resultFormat.  Possible values are: "object", "array", "xml", "flashvars", "text", "e4x".  Default value is "object", which converts XML to a hierarchical list of ActionScript objects.

6. Retriving Results via a Handler Function <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" creationComplete="service.send()"> <mx:HTTPService url="students.xml" result="handleResult(event)" /> <![CDATA[ import mx.rpc.events.ResultEvent; private function handleResult(e:ResultEvent):void { var resultObj: Object = e.result; … } ]]>

7. Passing Parameters to the Server <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" creationComplete="sendRequest()"> <![CDATA[ private function sendRequest():void { var params: Object = new Object(); params.count = 10; // # of records params.min_age = 20; // minimum age service.send(params); // Use HTTP GET (default) } ]]>

8. References and Resources  Adobe Flex 3.0 For Dummies, by Doug McCune, Deepa Subramaniam. Wiley Publishing, Inc. 2008