Question

Why does the load method of the URLStream class dispatch Event.OPEN instead of IOErrorEvent.IO_ERROR when the SWF is on a webserver and when trying to load an invalid URL?

The same doesn’t apply when running the SWF locally.

Sample code:

var CLS_UrlStream:URLStream = new URLStream(); // Initialize URLStream class instance.
CLS_UrlStream.addEventListener(Event.OPEN, FUN_StreamHandler); // Listen for successful connections.
CLS_UrlStream.addEventListener(IOErrorEvent.IO_ERROR, FUN_StreamHandler); // Listen for conenction errors.
CLS_UrlStream.load(new URLRequest("InvalidURL")); // Load file.

private function FUN_StreamHandler(FUN_PAR_Event:Event):void {
trace("EVENT TYPE: " + FUN_PAR_Event.type);
}
// Outputs: EVENT TYPE: open

Answer 1

When the SWF is running on the server and is requesting for a resource that doesn’t exist, the server actually sends an error message which counts as data, thus there is no error event. The same didn’t apply locally because there was no web server to respond with an error when a request for an nonexistent file is made. Discovered this by tracing live with the Monster Debugger.