Flex 4: Asynchronous Token

Flex is all about Event Driven Development

Consider an enterprise application in which a user can place purchase orders for some

parts and request price quotes from various suppliers. In this case, the user may click

several buttons, resulting in server-side calls to one or more destinations. On each click

event of the button, a RemoteObject sends a new request to the server.

Here’s the million-dollar question: how can the application code map arriving result

objects back to the initial requesters if they can come back to the client in an arbitrary

order?.

Ans: Asynchronous Token Pattern

The goal of the Asynchronous Token pattern is to properly route the processing on the

client in response to the data arriving asynchronously from the server.

OK, How do i design using it:

Flash 4 Builder can generate CallResponders for your service calls and what you all have

to do is write your business logic.

<fx:Script>

<![CDATA[

import mx.controls.Alert;

import mx.rpc.events.ResultEvent;

protected function getHelloString():void

{

getHelloStringResult.token = excelDbService.getHelloString();

}

protected function getHelloStringResult_resultHandler(event:ResultEvent):void

{

Alert.show( getHelloStringResult.lastResult);

}

]]>

</fx:Script>

<fx:Declarations>

<s:CallResponder id=”getHelloStringResult” result=”getHelloStringResult_resultHandler(event)”/>

<services:ExcelDbService id=”excelDbService” fault=”Alert.show(event.fault.faultString + ‘\n’ + event.fault.faultDetail)” showBusyCursor=”true”/>

</fx:Declarations>

reference: Enterprise Development with Flex and Flash 4 tutorials