Saving flash game state to server after window.onbeforeunload when swf is cross-domain

Question

My Facebook app is a flash game. I want the game swf to save its latest state to the server when the window unloads. Since I embed the swf with swfobject, I use its embed handler to add a onbeforeunload listener to window:

function embedHandler(event)        
{
shell=event.ref;
window.onbeforeunload=function(event)
{
    shell.message("save", null);
        //delay the unloading a bit so flash has time to contact server
    var now = new Date().getTime();
     var later=now+50;
     while (now < later)
     {
        now = new Date().getTime();
      }
     }
 }

Here's the problem. This works every time when the swf is loaded directly from the app (a rails app). It never works when the swf is loaded from Amazon.

All the cross-domain issues are worked out between the swf and the app--the rails app accepts calls from Amazon swf, and the Amazon swf loads data from the rails app.

ExternalInterface also works for both outgoing and ingoing calls. But I suspect this is nonetheless a browser security issue, since the inward-going ExternalInterface call only fails when:

1. it is called from inside the window.onbeforeunload handler
2. the swf originates from Amazon.

What is the problem? How does one unobtrusively save game state when the game is from a CDN and the save is triggered by onbeforeunload in Javascript? Or is there a better way to accomplish this same thing?

Testing in Firefox.

Answer 1

ExternalInterface also works for both outgoing and ingoing calls. But I suspect this is nonetheless a browser security issue, since the inward-going ExternalInterface call only fails when:

1. it is called from inside the window.onbeforeunload handler
2. the swf originates from Amazon.

From the sounds of it you worked out all the security issues.
It is more likely a lack of understanding on your part on what is going on behind the scene when onbeforeunload is triggered.
This is a function that will not wait for your "game.swf" to finish the call back via ExternalInterface.This is why you added a stalling mechanism to delay that process. However, I will assume here that this works from the rails app because that is a local server and you are not subject to the lag monster.
Now you might be thinking well I put in a delay it should work. Well that delay is on 50 milliseconds. Try increasing to to 5000(5 seconds) and you should see it start to work on the cdn.

The saving of data should be controlled via the flash app and not triggered by an outside source.
In the game itself you should have milestones that should trigger a save event.

In closing I do want to add that is by far the worst method you could use to save information up to a server. onbeforeunload is unreliable and is subject to cross browser issues let alone putting a lag loop in the JavaScript is just a bad idea and in the end just annoy your users to the point that they won't return.