Authentication for GWT based applications on Google App Engine

there is a way to use Java together with Google App Engine: GWT together with python-gwt-rpc. Although python-gwt-rpc has it's own means to allow authentication, there is also an easier way: just check in the Python code whether the user is authenticated and generate a login page or a page for hosting your GWT application.

...
from google.appengine.api import users

class MyHandler(webapp.RequestHandler):
 def get(self):
   user = users.get_current_user()
  if user is None:
      self.response.out.write('''Login page here...''')
  else:
      self.response.out.write('''GWT hosting page here...''')

here is how it looks in a live application