subtleties

Whew! I just finished a hell of a debugging session. My goal was to make Flash submit a url to tinyurl.com for minification.

My code worked locally (when I ran the swf on my desktop), but it didn't work in the browser. So I was pretty sure it was a security issue. But I couldn't understand why I wasn't getting a response from http://tinyurl.com, because they DO have a crossdomain.xml file. See: http://www.tinyurl.com/crossdomain.xml

hint: if you're smarter than I am, you may be able to guess the problem just via the previous paragraph.

Here's the code that didn't work:

send();

function send() : void
{
   var url : String = "http://www.google.com/search?q=cows";
   var urlLoader : URLLoader = new URLLoader();
   urlLoader.addEventListener( Event.COMPLETE, receive );
   urlLoader.load( new URLRequest( "http://www.tinyurl.com/api-create.php?url=" + url ) );
}

//this callback function never gets called!
function receive( event : Event ) : void
{
   var urlLoader : URLLoader = event.target as URLLoader;
   //output is a text field on the stage
   output.text = urlLoader.data;
}

Here's the working version. Can you spot the difference?

send();

function send() : void
{
   var url : String = "http://www.google.com/search?q=cows";
   var urlLoader : URLLoader = new URLLoader();
   urlLoader.addEventListener( Event.COMPLETE, receive );
   urlLoader.load( new URLRequest( "http://tinyurl.com/api-create.php?url=" + url ) );
}

function receive( event : Event ) : void
{
   var urlLoader : URLLoader = event.target as URLLoader;
   //output is a text field on the stage
   output.text = urlLoader.data;
}

Give up? The difference is in this statement:

BUGGY: urlLoader.load( new URLRequest( "http://www.tinyurl.com/api-create.php?url=" + url ) );

WORKING: urlLoader.load( new URLRequest( "http://tinyurl.com/api-create.php?url=" + url ) );

In case you still don't see it, the buggy version has a www in-front-of the url and the working version doesn't.

tinyurl's crossdomain.xml file is located at http://tinyurl.com/crossdomain.xml NOT http://www.tinyurl.com/crossdomain.xml.

But you'll get to it if you type it the "wrong" way into the browser, because most browser normalize urls. Flash doesn't. To Flash, there is no crossdomain.xml file, because it was specifically looking for one at the www address, and there isn't one there.

The scary thing is that my FIRST assumption was that it was a crossdomain.xml issue, so I watched the Activity Window in Safari as I ran my app (the bad version) in the browser. The Activity window showed that the crossdomain file was being accessed correctly. But apparently that was just the BROWSER accessing it correctly. Flash still thought of it as a bogus file, since it came from a www site.