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  • AS3 Promises - a guide and example
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Introduction

Hello world

https://promisesaplus.com/

http://spring.io/understanding/javascript-promises
http://www.html5rocks.com/en/tutorials/es6/promises/

You need to make 'ordinary' components Promise-ready.

Main.xml (package: default package)

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
			   xmlns:s="library://ns.adobe.com/flex/spark" 
			   xmlns:mx="library://ns.adobe.com/flex/mx" 
			   minWidth="955" 
			   minHeight="600"
			   creationComplete="creationCompleteHandler(event)">

	<fx:Script><![CDATA[

		import mx.controls.Alert;
		import mx.events.FlexEvent;
		import mx.rpc.http.HTTPService;

		import nl.ixms.HTTPServicePromise;

		import org.apache.flex.promises.interfaces.IThenable;

		private var httpServicePromise_:HTTPServicePromise;

		private function btnClickHandler(event:MouseEvent):void
		{
			httpServicePromise_.sendWithPromise().
				then(useFirstResultInAnotherPromise).
				then(showSecondResultInAlert);
		}

		private function creationCompleteHandler(event:FlexEvent):void
		{
			httpServicePromise_ = new HTTPServicePromise();
			httpServicePromise_.url = 'http://people.apache.org/~erikdebruin/promise.txt';
			httpServicePromise_.method = 'GET';
			httpServicePromise_.resultFormat = HTTPService.RESULT_FORMAT_TEXT;
		}

		private function showSecondResultInAlert(result:String):void
		{
			Alert.show(result);
		}

		private function useFirstResultInAnotherPromise(result:String):IThenable
		{
			var url:String = result.split('\n')[3];

			var anotherHTTPServicePromise:HTTPServicePromise = new HTTPServicePromise();
			anotherHTTPServicePromise.url = url;
			anotherHTTPServicePromise.method = 'GET';
			anotherHTTPServicePromise.resultFormat = HTTPService.RESULT_FORMAT_TEXT;

			return anotherHTTPServicePromise.sendWithPromise();
		}

	]]></fx:Script>

	<fx:Declarations />

	<s:VGroup>
		<s:Button label="Start the promises chain" click="btnClickHandler(event)"/>
	</s:VGroup>

</s:Application>

HTTPServicePromise.as (package: nl.ixms)

package nl.ixms
{

import mx.rpc.events.FaultEvent;
import mx.rpc.events.ResultEvent;
import mx.rpc.http.HTTPService;

import org.apache.flex.promises.Promise;
import org.apache.flex.promises.interfaces.IThenable;

public class HTTPServicePromise extends HTTPService
{

	public function HTTPServicePromise(rootURL:String=null, destination:String=null)
	{
		super(rootURL, destination);
	}

	public function sendWithPromise(parameters:Object=null):IThenable
	{
		return new Promise(function (fulfill:Function = null,
									 reject:Function = null):* {
			
			/* Link the service result events with the promise handlers */
			addEventListener(ResultEvent.RESULT, function (event:ResultEvent):void {
				fulfill(event.result);
			});
			addEventListener(FaultEvent.FAULT, function (event:FaultEvent):void {
				reject(event.message);
			});

			send(parameters);
		});
	}

}
}
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