How to make URLLoader return an AsyncToken?

Question

I was trying to retrieve binary data over HTTP for my Flex application, and was running into some stumbling blocks. HTTPService did not seem to deal with binary data well, people said to use URLLoader. But URLLoader does not have the nice AsyncToken/IResponder interface that HTTPService provides.

So, I did some searching and could not find anyone extending URLLoader to provide this kind of functionality. I went ahead and took a stab at it myself: http://pastebin.com/d7369d0e0

Basically it wraps a URLLoader and an AsyncToken, and maps the COMPLETE, IO_ERROR, and SECURITY_ERROR events from URLLoader to results/faults that get raised on the AsyncToken.

Basic usage:

var tidbitLoader:AsyncURLLoader = new AsyncURLLoader();
tidbitLoader.dataFormat = URLLoaderDataFormat.BINARY;

var asyncToken:AsyncToken = tidbitLoader.load(new URLRequest("http://localhost/SampleTidbit.swf"));

asyncToken.addResponder(this);

public function result(resultEvent:Object):void
{
    trace("result");
}

public function fault(faultEvent:Object):void 
{
    var fault:FaultEvent = faultEvent as FaultEvent;
    trace("fault: " + fault.toString());
}

Is this the right way to approach the problem? Are there existing solutions? I would love to hear feedback.

Thanks,

Karthik

So the binary data you want to read is a SWF? But you don't want to just run the SWF (like SWFLoader or Loader does)? Did you try to use HTTPService with the resultFormat set to text? — James Ward, Dec 28 '09 at 11:11
Hi James, I did try using HTTPService with resultFormat as text but then when I set the SWFLoader.source to the result of that call, the SWF would not load! When I try it with my AsyncURLLoader and get a ByteArray back as a result, it works. — Karthik, Dec 29 '09 at 22:38
Maybe you need to try and create a ByteArray using writeUTFBytes or something? — James Ward, Dec 30 '09 at 02:50
So that this can be closed I posed a more concise answer below. — James Ward, Dec 30 '09 at 16:04

score 1 · Accepted Answer · answered Dec 30 '09 at 16:04

Use the resultFormat = text on the HTTPService and then create a new ByteArray and call writeUTFBytes to write the text from the HTTPService result to the ByteArray. Then you should be able to set that ByteArray to a SWFLoader.source or call Loader.loadBytes.

score 0 · Answer 2 · answered Jan 28 '10 at 12:07

I have tried your solution James with an AIR 1.5 app, but I get the following error when I set the ByteArray on my SWFLoader.source. Any ideas? I thought I read somewhere that AIR changes the HTTP headers and this may be the cause? Thanks Ben.

[DEBUG] mx.messaging.Channel 'direct_http_channel' channel sending message: (mx.messaging.messages::HTTPRequestMessage)#0 body = (Object)#1 clientId = (null) contentType = "application/x-www-form-urlencoded" destination = "DefaultHTTP" headers = (Object)#2 httpHeaders = (Object)#3 messageId = "3044E76C-CF0E-2D5F-96BE-74CFF62098B0" method = "GET" recordHeaders = false timestamp = 0 timeToLive = 0 url = "http://www.myurl.com/test.jpg" [INFO] mx.messaging.Producer '4FA2CCF4-2B3E-4EAB-2873-74CFF612AA72' producer connected. [INFO] mx.messaging.Producer '4FA2CCF4-2B3E-4EAB-2873-74CFF612AA72' producer acknowledge of '3044E76C-CF0E-2D5F-96BE-74CFF62098B0'. [INFO] mx.rpc.http.HTTPService Decoding HTTPService response [DEBUG] mx.rpc.http.HTTPService Processing HTTPService response message: (mx.messaging.messages::AcknowledgeMessage)#0 body = "ÿØÿà Error #2044: Unhandled IOErrorEvent:. text=Error #2124: Loaded file is an unknown type.

How to make URLLoader return an AsyncToken?

2 Answers2