Please clarify: why is callback_url needed for desktop apps using OpenSocial REST?

After peruing MySPACEID I am still at loss how to do a simple login

authentication using REST APIs

request_token

authorize? - what is the need for callback_url?

 Hi Sopronos,

 Which document(s) were you looking at?

Desktop/Mobile apps have the same constraints as web apps, unfortunately. See the MyspaceID FAQ's here:

http://wiki.developer.myspace.com/index.php?title=MySpaceID_FAQs

Thanks,

Joel