CSC 2720Building Web Applications

FLEX –Working with Remote Data

Connecting with HTTP

Use HTTPService class to load any remote data via HTTP protocol

Steps: Create an instance of HTTPService that maps to a U

RL.

Invoke the send() method to retrieve the remote file asynchronously.

Retrieve the loaded data via the lastResult property.

Loading an XML File

<?xml version="1.0" encoding="utf-8"?><students> <student name="John Doe" id="08123456" age="21" /> <student name="Jane Dow" id="08999111" age="18" /> <student name="Gary Brown" id="07111222" age="19" /> <student name="Amy White" id="07000001" age="20" /></students>

students.xml

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.

<?xml version="1.0" encoding="utf-8"?><mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" creationComplete="service.send()">

<mx:HTTPService id="service" url="students.xml" />

<mx:DataGrid dataProvider="{service.lastResult.students.student}" > </mx:DataGrid></mx:Application>

HTTPService's resultFormat Property

<mx:HTTPService … resultFormat="object" />

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.

Retriving Results via a Handler Function<?xml version="1.0" encoding="utf-8"?><mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" creationComplete="service.send()">

<mx:HTTPService url="students.xml" result="handleResult(event)" />

<mx:Script> <![CDATA[ import mx.rpc.events.ResultEvent; private function handleResult(e:ResultEvent):void { var resultObj: Object = e.result; … } ]]> </mx:Script></mx:Application>

Passing Parameters to the Server<?xml version="1.0" encoding="utf-8"?><mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" creationComplete="sendRequest()">

<mx:HTTPService id="service" url="getStudents.php" />

<mx:Script> <![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)

} ]]> </mx:Script></mx:Application>

References and Resources Adobe Flex 3.0 For Dummies, by Doug McCune , Deepa S

ubramaniam. Wiley Publishing, Inc. 2008