Map Subdomain to specific AppEngine app version

I have a Python app at www.exa开发者_Python百科mple.com. I want to create a subdomain that will map to a different version of my app (actually a Java app). So want I want to do is: www.example.com -> example.appspot.com [0] subdomain.example.com -> subdomain.example.appspot.com [?]

Is it doable??

It's not currently possible to do this, except with a reverse proxy in front of your app (or by using your main version as such a reverse proxy).