Problem with Twitter basic authentication using AJAX

EDIT: This question is now redundant since Twitter no longer supports basic auth. I've left it up since it's relevant to anyone doing basic auth via AJAX on other services.

I'm developing a javascript App that needs, as part of its functionality, for users to be able to update their Twitter status. The App is designed to work on mobiles, and as such I don't really want to be sending users all the way over to the Twitter site to sign in; they should just be able to pass their credentials to the app, and I'll handle all the signin.

So I'm trying to use the Basic Auth with the restful API. My code looks like:

function postTweet(input){
            $.ajax( {
                type: "POST",
                url: "http://twitter.com/statuses/update.json",
                data: {status: input},
                dataType: "json",
                error: function() { alert("Some error occured"); },
                success: function() { alert("Success!"); },
                beforeSend: function(request) { request.setRequestHeader("Authorization", "Basic BASE64OFMYCREDENTIALS");}
                } ) ;
        }

So, as far as I'm aware, this should perform the authentication from the XMLHttpRequest header, and then post the status.

However, whenever I call this code, I get a "401 Unauthorized" error from Twitter.

Below are the request & response headers from firebug:

Request:

OPTIONS /statuses/update.json HTTP/1.1
Host: twitter.com
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.2) Gecko/20100115 Firefox/3.6
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-gb,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 115
Connection: keep-alive
Origin: null
Access-Control-Request-Method: POST
Access-Control-Request-Headers: authorization

Response:

HTTP/1.1 401 Unauthorized
Date: Sat, 13 Mar 2010 11:08:58 GMT
Server: hi
Status: 401 Unauthorized
WWW-Authenticate: Basic realm="Twitter API"
X-Runtime: 0.00204
Content-Type: application/json; charset=utf-8
Cache-Control: no-cache, max-age=300
Set-Cookie: guest_id=1268478538488; path=/
_twitter_sess=BAh7CDoPY3JlYXRlZF9hdGwrCPlyNlcnAToHaWQiJWUyN2YzYjc3OTk2NGQ3%250ANzJkYTA4MjYzOWJmYTQyYmUyIg开发者_Go百科pmbGFzaElDOidBY3Rpb25Db250cm9sbGVy%250AOjpGbGFzaDo6Rmxhc2hIYXNoewAGOgpAdXNlZHsA--d687808459872da0aa6a89cab35fd347300b4d07; domain=.twitter.com; path=/
Expires: Sat, 13 Mar 2010 11:13:58 GMT
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Length: 88
Connection: close

Any help with this would be much appreciated,

Thanks,

jelford

ps. I should mention I'm using JQuery, incase it's not clear.

Since the App was eventually going to be Client-Side only (It was designed for the JIL Mobile Platform), I decided to bite the bullet and do full OAuth, and just accept that it wasn't going to work if you opened it as a web page in Firefox.

What's puzzling to me is that - whilst I know POSTs will never work in the browser - I thought by setting the Auth headers in the HTTPRequest object and still making a GET request that would all go fine. Apparently not.

The point's mute now, since the App passed its deadline (got it finished :) ), but I thought someone might like to know that I didn't get it working through the basic auth route.