Hi Aman,
I don't know how to do it from Flash (and thus Flex). I doubt it's possible to do in straight ActionScript. That said, if it is possible to use JavaScript to get it, you can have JavaScript get it and then tell Flex via the Flex-Ajax Bridge (http://labs.adobe.com/wiki/index.php/Flex_Framework:FABridge).
Since I'm not a JavaScript / ActiveX guru, I don't know if this is possible. One solution I have seen from googling is here:
That said, why don't you just use a standard login system (e.g. login_generator, acts_as_authenticated, restful_authentication) on the Rails side (or roll your own, as is done in AWDwR) rather than trying to get the Windows login name from Flex?
This would be more reliable than relying on JavaScript (which the user may have disabled) and IE (since I assume that the ActiveX solution shown at codingforums is IE-only). Furthermore, why limit yourself to Windows clients when you can support Mac clients as well with *less* effort on your part?
Cheers, Peter Armstrong
P.S. Shameless plug: I have examples of Flex talking to Rails--both using login_generator and using restful_authentication--in my PDF-only book Flexible Rails (http://www.flexiblerails.com). You can download its MIT-licensed source code for free from http://www.flexiblerails.com/files/FlexibleRailsBookCode.zip to see how this works, regardless of whether you buy the book...
