Drag n drop desktop file to application as such in google

Is that possible to " Drag n drop file from desktop to
upload " in Ruby on rails application

   for example :   google (gmail) drag n drop attachments same as

this feature .

    Drag and drop functionality  working but how to upload the

file to the application ? through
ajax ? or other functionaltiy ?

     how to get file object through javascript which attributes

suits for that ?

     how to implement this ?..........

    Any ideas  greatly appreciated .....