Azure Mobile Service Single Sign on Microsoft Account

I have implemented single sign on using the WL api, but I only recently realized that I need to call mobileService.login on top of that to use the nice authentication features of Azure Mobile Services.

I followed this tutorial

http://www.windowsazure.com/en-us/develop/mobile/tutorials/single-sign-on-windows-8-js/#add-authentication

and added this piece of code:

var login = function () {
    return new WinJS.Promise(function (complete) {
        WL.init();

        WL.login({ scope: ["wl.signin", "wl.basic", "wl.birthday", "wl.emails"] }).then(function (result) {
            session = result.session;


            WinJS.Promise.join([
                WL.api({ path: "me", method: "GET" }),
                mobileService.login("microsoftaccount", session.authentication_token)
            ]).done(function (results) {
                var profile = results[0];
                var mobileServicesUser = results[1];

                var title = "Welcome " + profile.first_name + "!";
                var message = "You are now logged in as: " + mobileServicesUser.userId;
                var dialog = new Windows.UI.Popups.MessageDialog(message, title);
                dialog.showAsync().done(complete);
            });
        }, function (error) {
            session = null;
            var dialog = new Windows.UI.Popups.MessageDialog("You must log in.", "Login Required");
            dialog.showAsync().done(complete);
        });
    });
}

however on this line

mobileService.login("microsoftaccount", session.authentication_token)

my session.authentication_token is undefined. (I have an access_token)

If I don't pass the token, I am prompted to sign in every time I launch the app, which defeats the purpose of the integrated sign on.

Any ideas?

To get the authentication token, you need to pass the redirect URI to the call to WL.init:

WL.init({
    redirect_uri: "<< INSERT REDIRECT DOMAIN HERE >>"
});

Where the redirect domain must be the same as the one in your Live Connect application.