Cross-site AJAX requests

maybe JSONP can help.

NB youll have to change your messages to use json instead of xml

Edit

Major sites such as flickr and twitter support jsonp with callbacks etc

The post marked as the answer is erroneous: the iframes document is NOT able to access the parent. The same origin policy works both ways.

The fact is that it is not possible in any way to consume a rest based webservice using xmlhttprequest. The only way to load data from a different domain (without any framework) is to use JSONP. Any other solutions demand a serverside proxy located on your own domain, or a client side proxy located on the remote domain and som sort of cross-site communication (like easyXDM) to communicate between the documents.

The fact that this works in IE is a security issue with IE, not a feature.

Unfortunately cross-site scripting is prohibited, and the accepted work around is to proxy the requests through your own domain: do you really have no ability to add or modify server side code?

Furthermore, the secondary workaround - involving the aquisition of data through script tags - is only going to support GET requests, which you might be able to hack with a SOAP service, but not so much with the POST request to a RESTful service you describe.

I'm really not sure an AJAX solution exists, you might be back to a <form> solution.