Javascript cross domain - “allow” other domains?

Question

Description of steps

1. Write \"callback\" function on my custom page in my domain (called \"MyCallbackCallback\", for the sake of argument)

Answer 1

It’s not exactly clear from your question, but if you’re trying to use CORS, the server you’re requesting data from should add an Access-Control-Allow-Origin HTTP header, like so:

Access-Control-Allow-Origin: http://example.org/

Or, if it’s a public resource:

Access-Control-Allow-Origin: *

Older browsers don’t support CORS. If you need a fully cross-browser-compatible solution, use JSONP.

Answer 2

Have a look at Cross-Domain AJAX requests:

• https://developer.mozilla.org/En/HTTP_Access_Control
• http://msdn.microsoft.com/en-us/library/dd573303%28v=vs.85%29.aspx

JSONP is the only method compatible with older browsers though.

Answer 3

If you want cross-domain communication without serverside proxies (perfect for the kind of RPC that you are describing) then take a look at easyXDM.

You can find multiple demos here.